WO2022080487A1

WO2022080487A1 - METHOD FOR MANUFACTURING IRON (Fe)-NICKEL (Ni) ALLOY POWDER

Info

Publication number: WO2022080487A1
Application number: PCT/JP2021/038261
Authority: WO
Inventors: 雅也行延; 民燮申; しおり水野
Original assignee: 住友金属鉱山株式会社
Priority date: 2020-10-16
Filing date: 2021-10-15
Publication date: 2022-04-21
Also published as: US20230381861A1; JPWO2022080487A1; CN116391052A

Abstract

Provided is a method for manufacturing an iron-nickel alloy powder that has superior powder characteristics and magnetization characteristics. This method is a method for manufacturing an iron (Fe)-nickel (Ni) alloy powder that includes at least iron (Fe) and nickel (Ni) as magnetic metals. This method comprises the following steps: a preparation step in which a magnetic metal source, a nucleating agent, a complexing agent, a reducing agent, and a pH adjusting agent are prepared as starting materials; a crystallization step in which a reaction liquid that includes the starting materials and water is produced, and a crystallized powder that includes the magnetic metals is made to crystallize in the reaction liquid by a reduction reaction; and a recovery step in which the crystallized powder is recovered from the reaction liquid. The magnetic metal source includes a water-soluble iron salt and a water-soluble nickel salt, the nucleating agent is a water-soluble salt of a metal that is more noble than nickel, and the complexing agent is at least one type of substance selected from the group consisting of a hydroxy carboxylic acid, a salt of a hydroxy carboxylic acid, and a derivative of a hydroxy carboxylic acid. The reducing agent is hydrazine (N2H4), and the pH adjusting agent is an alkali hydroxide.

Description

Method for manufacturing iron (Fe) -nickel (Ni) alloy powder

The present invention relates to a method for producing an iron (Fe) -nickel (Ni) alloy powder.

The iron-nickel alloy known as permalloy is a soft magnetic material with high magnetic permeability and is used for the magnetic core of magnetic parts such as choke coils and inductors. In particular, iron-nickel alloy powder is used as a material for a compact core (compact magnetic core) for a magnetic core obtained by compression molding the iron-nickel alloy powder.

Various types of permalloy such as 78 permalloy (Permalloy A) and 45 permalloy are known, and they are used properly according to their magnetic characteristics and applications. 78 Permalloy is an iron-nickel alloy having a nickel content of about 78.5% by mass, and is characterized by having a high magnetic permeability. 45 Permalloy is an iron-nickel alloy having a nickel content of 45% by mass, and is characterized by having a slightly low magnetic permeability but a high saturation magnetic flux density.

In recent years, mobile devices such as laptop computers and smartphones have been rapidly becoming smaller and more sophisticated. Along with this, magnetic components such as inductors are required to cope with higher frequencies in addition to improving magnetic characteristics. For that purpose, the material of the dust core is required to have a high magnetic flux density and to reduce the loss. Losses mainly include hysteresis loss and eddy current loss. In order to suppress the hysteresis loss, it is effective to lower the coercive force of the alloy powder. On the other hand, in order to suppress eddy current loss, a thin insulating coating is applied to the surface of the alloy powder particles to reduce the eddy current between the particles, to make the alloy powder finer, and to reduce the particle size distribution. Is valid. This is because the presence of coarse particles facilitates the flow of eddy currents and causes loss due to Joule heat.

As a method for producing fine alloy powder, dry methods such as atomization method, gas phase reduction method and dry reduction method have been conventionally known. The atomizing method is a method in which water or gas is sprayed on a molten metal to quench and solidify the molten metal. The gas phase reduction method is a method for hydrogen reducing a metal halide in a gas phase state. The dry reduction method is a method of reducing a metal oxide using a reducing agent.

For example, Patent Document 1 describes that a Ni—Fe-based alloy powder used as a material for a noise filter, a choke coil, an inductor, etc. is manufactured by a vapor phase reduction method (Patent Document 1 [0001] and []. 0014]). Further, Patent Document 1 states that a mixture of NiCl ₂ and FeCl ₃ is heated and vaporized chloride and hydrogen gas are brought into contact with each other to cause a reduction reaction to produce a fine powder of a Ni—Fe alloy. It is disclosed (Patent Document 1 [0016]). Further, Patent Document 2 describes that Fe—Ni alloy powder used as a material for electronic parts such as choke coils and inductors is produced by reducing the oxides of Fe and Ni in a reducing gas. (Claim 1 of Patent Document 2).

On the other hand, it has been proposed to produce finer alloy powders using the wet method. For example, Patent Document 3 describes nickel-iron alloy nanoparticles by adding a reducing agent such as hydrazine to an aqueous solution containing a nickel salt and an iron salt to simultaneously reduce the nickel ions and iron ions contained in the aqueous solution. A method for producing nickel-iron alloy nanoparticles, which is characterized by producing nickel-iron alloy nanoparticles, is disclosed (claims 1 to 6 of Patent Document 3). Further, according to this production method, nickel-iron alloy nanoparticles having an average primary particle of 200 nm or less, which is suitable as a filler for imparting magnetic properties, can be efficiently produced on an industrial scale at a low production cost. It is said that this can be done (Patent Document 3 [0015]).

Japanese Patent Application Laid-Open No. 2003-193160 Japanese Unexamined Patent Publication No. 2012-197474 Japanese Unexamined Patent Publication No. 2008-0249461

Although it has been proposed to produce fine alloy powder by the dry method or the wet method as described above, there is room for improvement in the conventional technique in obtaining an alloy powder having excellent powder characteristics. For example, the alloy powder produced by the atomizing method has a large average particle size of several μm or more, and does not sufficiently meet the demand for miniaturization. Further, in the gas phase reduction method proposed in Patent Document 1, the particle size distribution of the obtained alloy powder is wide. Therefore, the alloy powder contains coarse particles, which is insufficient for reducing the eddy current loss. There is also a problem that the composition and particle size of the alloy powder are not stable. Since the dry reduction method proposed in Patent Document 2 requires high-temperature heating, there is a problem that the obtained alloy powder is easily sintered to form coarse agglomerated particles.

Unlike the dry method, the wet method proposed in Patent Document 3 has an advantage that coarse agglomerated particles are difficult to be generated because the reduction reaction proceeds at a low temperature. Further, even if the agglomerated particles are formed, the agglomerated particles are easily crushed because the bonds between the particles are not strong. However, in the method proposed in Patent Document 3, it is necessary to use a large amount of hydrazine as a reducing agent. Therefore, the cost of the reducing agent is significantly increased, which is not practical. Moreover, it cannot be said that the particle size distribution of the obtained alloy powder is sufficiently small.

The present inventors have conducted diligent studies in view of such conventional problems. As a result, it was found that an alloy powder having excellent powder characteristics and magnetic properties can be obtained by using a specific nucleating agent and a complexing agent in producing an iron-nickel alloy powder by a wet method. rice field. In addition, when cobalt with a predetermined content is added when the iron content is high, due to the reduction reaction promoting action and spheroidizing promoting action of cobalt, the amount of reducing agent used is very small, the aggregation is small, the surface is smooth, and the saturation magnetic flux is flux. We also obtained the finding that a spherical alloy powder with a high density can be obtained.

The present invention has been completed based on such findings, and an object of the present invention is to provide a method for producing an iron-nickel alloy powder having excellent powder characteristics and magnetic characteristics.

The present invention includes the following aspects (1) to (32). In the present specification, the expression "-" includes the numerical values at both ends thereof. That is, "X to Y" is synonymous with "X or more and Y or less".

(1) A method for producing an iron (Fe) -nickel (Ni) alloy powder containing at least iron (Fe) and nickel (Ni) as magnetic metals, wherein the method is as follows;
Preparation process for preparing magnetic metal sources, nucleating agents, complexing agents, reducing agents, and pH adjusters as starting materials,
A crystallization step of preparing a reaction solution containing the starting material and water and crystallizing the crystallization powder containing the magnetic metal in the reaction solution by a reduction reaction, and recovering the crystallization powder from the reaction solution. With a collection process,
The magnetic metal source contains a water-soluble iron salt and a water-soluble nickel salt, and contains.
The nucleating agent is a water-soluble salt of a metal that is noble than nickel.
The complexing agent is at least one selected from the group consisting of hydroxycarboxylic acids, salts of hydroxycarboxylic acids, and derivatives of hydroxycarboxylic acids.
The reducing agent is hydrazine (N ₂ H ₄ ).
The method, wherein the pH regulator is alkali hydroxide.

(2) The water-soluble iron salt is at least one selected from the group consisting of ferrous chloride (FeCl ₂ ), ferrous sulfate (FeSO ₄ ), and ferrous nitrate (Fe (NO ₃ ) ₂ ). There is the method of (1) above.

(3) The water-soluble nickel salt is at least one selected from the group consisting of nickel chloride (NiCl ₂ ), nickel sulfate (NiSO ₄ ), and nickel nitrate (Ni (NO ₃ ) ₂ ). Or the method of (2).

(4) The method according to any one of (1) to (3) above, wherein the nucleating agent is at least one selected from the group consisting of a copper salt, a palladium salt, and a platinum salt.

(5) The complexing agent is at least one hydroxycarboxylic acid selected from tartaric acid ((CH (OH) COOH) ₂ ) and citric acid (C (OH) (CH ₂ COOH) ₂ COOH). Any method from 1) to (4).

(6) The method according to any one of (1) to (5) above, wherein the pH adjuster is at least one selected from sodium hydroxide (NaOH) and potassium hydroxide (KOH).

(7) The magnetic metal further contains cobalt (Co), and the magnetic metal further contains cobalt (Co).
The method according to any one of (1) to (6) above, wherein the magnetic metal source further contains a water-soluble cobalt salt.

(8) In the magnetic metal, the iron (Fe) content is 60 mol% or more and 85 mol% or less, and the cobalt (Co) content is 10 mol% or more and 30 mol% or less.
In the magnetic metal source, the content ratio of the water-soluble iron salt is 60 mol% or more and 85 mol% or less, and the content ratio of the water-soluble cobalt salt is 10 mol% or more and 30 mol% or less. Method.

(9) The water-soluble cobalt salt is at least one selected from the group consisting of cobalt chloride (CoCl ₂ ), cobalt sulfate (CoSO ₄ ), and cobalt nitrate (Co (NO ₃ ) ₂ ). Or the method of (8).

(10) The starting material is two or more primary amino groups (-NH ₂ ), one primary amino group (-NH ₂ ) and one or more secondary amino groups (-NH-). ), Or the method according to any one of (1) to (9) above, further comprising an amine compound containing two or more secondary amino groups (-NH-) in the molecule.

(11) The method of (10) above, wherein the amine compound is at least one of an alkylene amine and an alkylene amine derivative.

(12) The alkyleneamine and / or the alkyleneamine derivative has at least the structure represented by the following (A), in which the nitrogen atom of the amino group in the molecule is bonded via a carbon chain having 2 carbon atoms. 11) Method.

(13) The amine compounds include ethylenediamine (H ₂ NC ₂ H ₄ NH ₂ ), diethylene triamine (H ₂ NC ₂ H ₄ NHC ₂ H ₄ NH ₂ ), and triethylene tetramine (H ₂ N (C ₂ H ₄ NH)). ₂ C ₂ H ₄ NH ₂ ), Tetraethylene Pentamine (H ₂ N (C ₂ H ₄ NH) ₃ C ₂ H ₄ NH ₂ ), Pentaethylene Hexamine (H ₂ N (C ₂ H ₄ NH) ₄ C ₂ ) At least one alkylene amine selected from the group consisting of H ₄ NH ₂ ) and propylenediamine (CH ₃ CH (NH ₂ ) CH ₂ NH ₂ ) and / or tris (2-aminoethyl) amine (N (C ₂ ). H ₄ NH ₂ ) ₃ ), N- (2-aminoethyl) ethanolamine (H ₂ NC ₂ H ₄ NHC ₂ H ₄ OH), N- (2-aminoethyl) propanolamine (H ₂ NC ₂ H ₄ NHC) ₃ H ₆ OH), 2,3-diaminopropionic acid (H ₂ NCH ₂ CH (NH) COOH), ethylenediamine-N, N'-diacetic acid (HOOCCH ₂ NHC ₂ H ₄ NHCH ₂ COOH), and 1, 2 -The method according to any one of (10) to (12) above, which is at least one alkylene amine derivative selected from the group consisting of cyclohexanediamine (H ₂ NC ₆ H10NH ₂ ).

(14) The method according to any one of (10) to (13) above, wherein the blending amount of the amine compound with respect to the total amount of the magnetic metal is 0.01 mol% or more and 5.00 mol% or less.

(15) When preparing the reaction solution in the crystallization step, the metal salt raw material solution in which the magnetic metal source, the nucleating agent, and the complexing agent were dissolved in water, and the reducing agent were dissolved in water. A reducing agent solution and a pH adjusting solution in which the pH adjusting agent is dissolved in water are prepared, and the metal salt raw material solution and the pH adjusting solution are mixed to form a mixed solution, and the mixed solution and the reducing agent are prepared. The method according to any one of (1) to (14) above, wherein the solutions are mixed.

(16) The method of (15) above, wherein when preparing the reaction solution, the pH adjusting solution and the reducing agent solution are sequentially added to the metal salt raw material solution and mixed.

(17) The method according to (15) or (16) above, wherein the time required for mixing the mixed solution and the reducing agent solution is 1 second or more and 180 seconds or less.

(18) When preparing the reaction solution in the crystallization step, the metal salt raw material solution in which the magnetic metal source, the nucleating agent, and the complexing agent are dissolved in water, the reducing agent, and the pH adjusting agent are used. The method according to any one of (1) to (14) above, wherein a reducing agent solution dissolved in water is prepared, and the metal salt raw material solution and the reducing agent solution are mixed.

(19) When preparing the reaction solution, the reducing agent solution is added to the metal salt raw material solution, or conversely, the metal salt raw material solution is added to the reducing agent solution and mixed. the method of.

(20) The method according to (18) or (19) above, wherein the time required for mixing the metal salt raw material solution and the reducing agent solution is 1 second or more and 180 seconds or less.

(21) In the crystallization step, an additional raw material solution in which at least one of the water-soluble nickel salt and the water-soluble cobalt salt is dissolved in water is further added to the reaction solution before the reduction reaction is completed. The method according to any one of (1) to (20) above, which comprises mixing.

(22) The method according to any one of (15) to (21) above, wherein the amine compound is added to at least one of the metal salt raw material solution, the reducing agent solution, the pH adjusting solution, and the reaction solution.

(23) The temperature of the reaction solution at the start of crystallization of the crystallization powder (reaction start temperature) is 40 ° C. or higher and 90 ° C. or lower, and the temperature of the reaction solution held during crystallization after the start of crystallization (reaction). The method according to any one of (1) to (22) above, wherein the holding temperature) is 60 ° C. or higher and 99 ° C. or higher.

(24) Further, a crushing step of crushing the agglomerated particles contained in the crystallization powder by subjecting the crystallization powder after the recovery step or the crystallization powder in the middle of the recovery step to a crushing treatment using collision energy. The method according to any one of (1) to (23) above.

(25) The method according to (24) above, wherein the crystallization powder after the recovery step is crushed by dry crushing or wet crushing, or the crystallization powder during the recovery step is crushed by wet crushing.

(26) The method of (25) above, wherein the drywall crushing is spiral jet crushing.

(27) The method of (25) above, wherein the wet crushing is high pressure fluid collision crushing.

(28) The crystallization powder after the recovery step or the crystallization powder in the middle of the recovery step is heat-treated in an inert atmosphere, a reducing atmosphere, or a vacuum atmosphere at a temperature of more than 150 ° C. and 400 ° C. or lower. The method according to any one of (1) to (27) above, further comprising a high-temperature heat treatment step for improving the composition uniformity in the particles of the iron (Fe) -nickel (Ni) alloy powder.

(29) Insulation coating treatment is applied to the crystallization powder obtained through the recovery step to form an insulation coat layer made of a metal oxide on the particle surface of the crystallization powder, thereby improving the insulation between the particles. The method according to any one of (1) to (28) above, further comprising a coating step.

(30) In the insulating coating step, the crystallization powder is dispersed in a mixed solvent containing water and an organic solvent, and a metal alkoxide is further added and mixed with the mixed solvent to prepare a slurry, and the metal alkoxide is prepared in the slurry. Is hydrolyzed and dehydrated and shrunk to form an insulating coat layer made of a metal oxide on the surface of the particles of the crystallization powder, and then the crystallization powder on which the insulating coat layer is formed is recovered from the slurry. )the method of.

(31) The method according to (30) above, wherein the metal alkoxide contains silicon alkoxide (alkyl silicate) as a main component, and the metal oxide contains silicon dioxide (SiO ₂ ) as a main component.

(32) The method according to (30) or (31) above, wherein the hydrolysis of the metal alkoxide is carried out in the coexistence of a base catalyst (alkali catalyst).

According to the present invention, there is provided a method for producing an iron-nickel alloy powder having excellent powder properties and magnetic properties.

It is a process diagram which provides the explanation of the manufacturing method of the alloy powder of this embodiment. It is a process diagram which provides the description of reaction liquid preparation and alloy powder production in 1st Embodiment. It is a process diagram which provides the description of reaction liquid preparation and alloy powder production in 1st Embodiment. It is a process diagram which provides the description of the reaction liquid preparation and the alloy powder production in the 2nd aspect. It is a process diagram which provides the description of the reaction liquid preparation and the alloy powder production in the 2nd aspect. It is a process diagram which provides the description of the reaction liquid preparation and the alloy powder production in the 3rd aspect. It is a figure which shows the liquid temperature transition in the reaction tank in the crystallization step of Example 1. FIG. 6 is an SEM image of the alloy powder obtained in Example 1. 6 is an SEM image of the alloy powder obtained in Example 2. 6 is an SEM image of the alloy powder (before and after the spiral jet crushing treatment) obtained in Example 6. It is the STEM image of the alloy powder (before and after high temperature heat treatment) obtained in Example 8, and the EDS ray analysis result. It is the STEM image of the particle cross section of the alloy powder obtained in Example 9, and the EDS line analysis result. 6 is an SEM image of the alloy powder obtained in Example 10. 6 is an SEM image of the alloy powder (before and after the insulating coating treatment) obtained in Example 12. 6 is an SEM image of the alloy powder obtained in Example 13. 6 is an SEM image of the alloy powder obtained in Example 14. 6 is an SEM image of the alloy powder obtained in Comparative Example 1. 6 is an SEM image of the alloy powder obtained in Comparative Example 2. 6 is an SEM image of the alloy powder obtained in Comparative Example 3.

A specific embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described. The present invention is not limited to the following embodiments, and various modifications can be made without changing the gist of the present invention.

<< 1. Manufacturing method of iron-nickel alloy powder >>
The method for producing an iron (Fe) -nickel (Ni) alloy powder of the present embodiment is as follows: a starting material containing a magnetic metal source, a nucleating agent, a complexing agent, a reducing agent, and a pH adjusting agent is prepared. A preparatory step, a crystallization step of preparing a reaction solution containing the starting material and water, and crystallization of the crystallization powder containing the magnetic metal by a reduction reaction in the reaction solution, and crystallization from the obtained reaction solution. It is provided with a recovery step of recovering the sample. Here, the iron (Fe) -nickel (Ni) alloy powder contains at least iron (Fe) and nickel (Ni) as magnetic metals. The magnetic metal source also contains a water-soluble iron salt and a water-soluble nickel salt. The nucleating agent is a water-soluble salt of a metal that is noble than nickel. The complexing agent is at least one selected from the group consisting of hydroxycarboxylic acids, salts of hydroxycarboxylic acids, and derivatives of hydroxycarboxylic acids. The reducing agent is hydrazine (N ₂ H ₄ ).

The iron (Fe) -nickel (Ni) -based alloy powder of the present embodiment (hereinafter, may be simply referred to as "alloy powder") contains at least iron (Fe) and nickel (Ni). Further, the alloy powder may contain cobalt (Co), if necessary. That is, the alloy powder may be an iron-nickel alloy powder containing only iron and nickel, or an iron-nickel-cobalt alloy powder containing iron, nickel and cobalt. Iron, nickel and cobalt are all magnetic metals exhibiting ferromagnetism. Therefore, iron-nickel alloy powder and iron-nickel-cobalt alloy powder have a high saturation magnetic flux density and are excellent in magnetic characteristics. In the present specification, magnetic metal is a general term for iron, nickel and cobalt. That is, when the alloy does not contain cobalt, the magnetic metal is a general term for iron and nickel, and when the alloy contains cobalt, it is a general term for iron, nickel and cobalt.

The proportions of iron (Fe), nickel (Ni) and cobalt (Co) contained in the alloy powder of this embodiment are not particularly limited. The amount of iron may be 10 mol% or more and 95 mol% or less, 25 mol% or more and 90 mol% or less, and 40 mol% or more and 80 mol% or less. The amount of nickel may be 5 mol% or more and 90 mol% or less, 10 mol% or more and 75 mol% or less, and 20 mol% or more and 60 mol% or less. The amount of cobalt may be 0 mol% or more and 40 mol% or less, and may be 5 mol% or more and 20 mol% or less. However, the total amount of iron, nickel and cobalt is 100 mol% or less.

The alloy powder of this embodiment does not exclude the inclusion of additive components other than magnetic metals (Fe, Ni and Co). Examples of such an additive component include copper (Cu) and / or boron (B). However, in order to maximize the effect based on the magnetic metal, it is preferable that the content of the additive component other than the magnetic metal is small. The content of the components other than the magnetic metal may be 10% by mass or less, 5% by mass or less, 1% by mass or less, or 0% by mass. Further, the alloy powder may contain impurities (unavoidable impurities) that are inevitably mixed in during the manufacturing process. Examples of such unavoidable impurities include oxygen (O), carbon (C), chlorine (Cl), and alkaline components (Na, K, etc.). Since unavoidable impurities may cause deterioration of the characteristics of the alloy powder, it is preferable to suppress the amount as much as possible. The amount of unavoidable impurities is preferably 5% by mass or less, more preferably 3% by mass or less, for oxygen (O) contained in the oxide film always formed on the surface of the alloy powder. On the other hand, the carbon (C), chlorine (Cl), and alkaline component (Na, K, etc.) are preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less. The alloy powder may contain a magnetic metal and may have a composition consisting of residual unavoidable impurities.

The method for producing the alloy powder of the present embodiment includes at least a preparation step, a crystallization step, and a recovery step. Further, if necessary, a crushing step and a high-temperature heat treatment step may be provided after the recovery step or during the recovery step, or an insulating coating step may be provided after the recovery step. FIG. 1 schematically shows an example of a process in the manufacturing method of the present embodiment. Although FIG. 1 shows a crushing treatment, a high-temperature heat treatment, and an insulating coating treatment, these treatments may be provided as needed and are not essential treatments. Further, when the crushing treatment, the high temperature heat treatment, and / or the insulating coating treatment are performed, there is no particular restriction on the order in which these treatments are performed. Speaking of which, it is preferable to perform the crushing treatment after the high temperature heat treatment. This is because the connection (bonding) between the alloy particles strengthened by the high temperature heat treatment can be reduced or eliminated. Further, it is preferable to perform the crushing treatment before the insulating coating. This is because it is possible to uniformly insulate and coat the entire surface of each of the alloy particles in which the connection is reduced or eliminated. On the other hand, when the alloy particles are connected, the insulating coat layer is not formed at the connected portion. Therefore, it is preferable to reduce or eliminate the connection as much as possible before the insulating coating treatment. Details of each step will be described below.

<Preparation process>
In the preparation step, a magnetic metal source, a nucleating agent, a complexing agent, a reducing agent, and a pH adjusting agent are prepared as starting materials. The magnetic metal source is a raw material for iron and nickel, but may contain a cobalt raw material if necessary. Further, the starting material may contain an amine compound. Each raw material will be described below.

(A) Magnetic metal source The magnetic metal source is a raw material for a magnetic metal and contains at least a water-soluble iron salt and a water-soluble nickel salt. The iron salt is a raw material (iron source) for the iron component contained in the alloy powder, and is not particularly limited as long as it is an easily water-soluble iron salt. Examples of the iron salt include iron chloride containing divalent and / or trivalent iron ions, iron sulfate, iron nitrate, or a mixture thereof. The water-soluble iron salt is preferably at least one selected from the group consisting of ferrous chloride (FeCl ₂ ), ferrous sulfate (FeSO ₄ ), and ferrous nitrate (Fe (NO ₃ ) ₂ ). .. The nickel salt is a raw material (nickel source) for the nickel component contained in the alloy powder, and is not particularly limited as long as it is an easily water-soluble nickel salt. The water-soluble nickel salt is preferably at least one selected from the group consisting of nickel chloride (NiCl ₂ ), nickel sulfate (NiSO ₄ ), and nickel nitrate (Ni (NO ₃ ) ₂ ), particularly preferably chloride. It is at least one selected from the group consisting of nickel (NiCl ₂ ) and nickel sulfate (NiSO ₄ ).

If necessary, the magnetic metal may further contain cobalt (Co), and the magnetic metal source may further contain a water-soluble cobalt salt. This makes it possible to produce iron-nickel-cobalt alloy powder. The iron-nickel-cobalt alloy powder in which a part of iron or nickel is replaced with cobalt is characterized by having a particularly high saturation magnetic flux density.

The water-soluble cobalt salt has an action of promoting a reduction reaction (reduction promoting action) at the time of crystallization of the alloy powder, and particularly when the content ratio of iron (Fe) in the magnetic metal is as large as 60 mol% or more. , This reduction promoting action becomes more remarkable. Further, the water-soluble cobalt salt also has an action of turning the alloy powder into spherical particles having a smooth surface (spheroidizing promoting action). Therefore, if the content of the water-soluble iron salt is 60 mol% or more and 85 mol% or less and the content of the water-soluble cobalt salt is 10 mol% or more and 30 mol% or less in the magnetic metal source, hydrazine as a reducing agent is used. Even if the amount used is very small, an iron-nickel-cobalt alloy powder having an extremely high saturation magnetic flux density (for example, 2T (tesla) or more) and a smooth surface can be obtained. This alloy powder has, for example, an iron content of 60 mol% or more and 85 mol% or less, and a cobalt content of 10 mol% or more and 30 mol% or less.

The water-soluble cobalt salt is not particularly limited as long as it is an easily water-soluble cobalt salt. The water-soluble cobalt salt is preferably at least one selected from the group consisting of cobalt chloride (CoCl ₂ ), cobalt sulfate (CoSO ₄ ), and cobalt nitrate (Co (NO ₃ ) ₂ ), and is particularly preferably chloride. It is at least one selected from the group consisting of cobalt (CoCl ₂ ) and cobalt sulfate (CoSO ₄ ).

(B) Nuclear agent A nuclear agent is a water-soluble salt of a metal that is noble than nickel. This nucleating agent (a water-soluble salt of a metal nobler than nickel) is preferentially reduced in the reaction solution in the subsequent crystallization step to generate initial nuclei, and the initial nuclei promote the precipitation of crystallization powder. It works. Here, a metal nobler than nickel is a metal having a higher potential in the standard potential series than nickel in an aqueous solution. It can also be said that a metal nobler than nickel is a metal having a lower ionization tendency than nickel. Examples of such metals include tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), copper (Cu), silver (Ag), palladium (Pd), iridium (Ir), and platinum (Pt). , And gold (Au).

By using a water-soluble salt of a metal nobler than nickel as the nucleating agent, it is possible to control the formation of the crystallization powder in the reaction solution in the subsequent crystallization step. For example, if the amount of the nucleating agent added is increased, fine crystallization powder can be obtained. That is, in the crystallization step, magnetic metal ions and complex ions contained in the reaction solution are reduced and precipitated to form crystallization powder. Among magnetic metals, nickel has more noble properties than iron and cobalt, and has a low ionization tendency. Therefore, if a water-soluble salt (nuclear agent) of a metal nobler than nickel is contained in the reaction solution, the metal nobler than nickel is reduced and precipitated prior to all the magnetic metals. A metal nobler than the precipitated nickel acts as an initial nucleus, and this initial nucleus grows into grains to form a crystallization powder consisting of a magnetic metal. Control becomes possible.

The nucleating agent is not particularly limited as long as it is a water-soluble salt of a metal nobler than nickel. However, the nucleating agent is preferably at least one selected from the group consisting of copper salts, palladium salts, and platinum salts. Copper (Cu), palladium (Pd) and platinum (Pt) have particularly strong noble properties and have a low ionization tendency. Therefore, it is particularly excellent in its effect as a nuclear agent. Examples of the water-soluble copper salt include, but are not limited to, copper sulfate. Further, examples of the water-soluble palladium salt include, but are not limited to, palladium (II) chloride sodium, palladium (II) ammonium chloride, palladium (II) nitrate, palladium (II) sulfate and the like. The nucleating agent is particularly preferably a palladium salt. When the palladium salt is used, the particle size of the crystallization powder (alloy powder) can be controlled more finely.

The blending amount of the nucleating agent may be adjusted so that the particle size of the finally obtained alloy powder becomes a desired value. For example, the blending amount of the nucleating agent with respect to the total amount of the magnetic metal may be 0.001 mol ppm or more and 5.0 mol ppm or less, and may be 0.005 mol ppm or more and 2.0 mol ppm or less. By setting the blending amount of the nucleating agent within this range, an alloy powder having an average particle size of 0.2 μm or more and 0.6 μm or less can be obtained. However, the blending amount of the nucleating agent is not limited to the above range. For example, in the case of producing a fine alloy powder having an average particle size of less than 0.2 μm, the blending amount of the nucleating agent may be set to more than 5.0 mol ppm.

(C) Complexing agent The complexing agent is at least one selected from the group consisting of hydroxycarboxylic acid, a salt of hydroxycarboxylic acid, and a derivative of hydroxycarboxylic acid. This complexing agent (hydroxycarboxylic acid or the like) has an effect of homogenizing the reaction in the subsequent crystallization step. That is, the magnetic metal component is dissolved as magnetic metal ions (Fe ²⁺ , Ni ²⁺ , etc.) in the reaction solution, but the reaction solution becomes strongly alkaline due to the pH adjuster (NaOH, etc.), so that it dissolves in the reaction solution. The amount of magnetic metal ions is extremely small. However, in the presence of the complexing agent, the magnetic metal component can be dissolved in large amounts as complex ions (Fe complex ion, Ni complex ion, etc.). Due to the presence of such complex ions, the reduction reaction rate is increased, the local uneven distribution of the magnetic metal component is suppressed, and the reaction system can be made uniform. The complexing agent also has the effect of changing the complex stability balance of a plurality of magnetic metal ions in the reaction solution. Therefore, in the presence of the complexing agent, the reduction reaction of the magnetic metal changes, and the balance between the nucleation rate and the grain growth rate changes. By using the complexing agent (hydroxycarboxylic acid, etc.) specified in the present embodiment, the above-mentioned actions work in a complex manner, and the reaction proceeds in a preferable direction, resulting in powder characteristics of the alloy powder obtained. Particle size, particle size distribution, sphericality, surface texture of particles) are improved. Further, the alloy powder having improved powder characteristics has excellent filling property and is suitable as a raw material for a powder core. In this respect, it can be said that the complexing agent (hydroxycarboxylic acid or the like) of the present embodiment has functions as a reduction reaction accelerator, a spheroidization accelerator, and a surface smoothing agent. Suitable complexing agents include at least one hydroxycarboxylic acid selected from tartaric acid ((CH (OH) COOH) ₂ ) and citric acid (C (OH) (CH ₂ COOH) ₂ COOH).

The blending amount of the complexing agent with respect to the total amount of the magnetic metal is preferably 5 mol% or more and 100 mol% or less, more preferably 10 mol% or more and 75 mol% or less, and further preferably 15 mol% or more and 50 mol% or less. When the blending amount is 5 mol% or more, the functions as a reduction reaction accelerator, a spheroidizing accelerator, and a surface smoothing agent are sufficiently exhibited, so that the powder characteristics (particle size, particle size distribution, spherical shape) of the alloy powder are exhibited. (Characteristics, surface texture of particles) will be even better. Further, when the blending amount is 100 mol% or less, the amount of the complexing agent used can be suppressed without causing a large difference in the degree of functional expression as the complexing agent, which leads to a reduction in manufacturing cost.

(D) Reducing agent The reducing agent is hydrazine (N ₂ H ₄ , molecular weight: 32.05). This reducing agent (hydrazine) has an action of reducing magnetic metal ions and complex ions in the reaction solution in the subsequent crystallization step. Hydrazine has the advantages of having strong reducing power and not producing by-products associated with the reducing reaction in the reaction solution. Moreover, it is easy to obtain high-purity hydrazine with few impurities.

As hydrazine, in addition to anhydrous hydrazine, hydrazine hydrate, hydrazine hydrate ₍ _N2 H4 · _H2O , molecular weight: 50.06) is known. Either may be used. As the water-holding hydrazine, for example, commercially available industrial grade 60% by mass water-holding hydrazine can be used.

The blending amount of the reducing agent largely depends on the composition of the iron (Fe) -nickel (Ni) alloy powder, and the larger the content ratio of iron that is difficult to reduce, the larger the amount is required. In addition to the composition of the alloy powder, it is also affected by the temperature of the reaction solution, the blending amount of the complexing agent and the pH adjuster, and the like. For example, when the iron content in the iron-nickel alloy powder is 60 mol% or less, the blending amount of the reducing agent with respect to the total amount of magnetic metals is preferably 1.8 or more and 7.0 or less in terms of molar ratio. It is more preferably 0 or more and 6.0 or less, and further preferably 2.5 or more and 5.0 or less. When the iron content of the iron-nickel alloy powder is more than 60 mol% and 75 mol% or less, the blending amount of the reducing agent with respect to the total amount of magnetic metals is 2.5 or more and 9.0 or less in terms of molar ratio. Is preferable, and 3.5 or more and 8.0 or less are more preferable. When the iron content of the iron-nickel alloy powder is more than 75 mol% and 95 mol% or less, the blending amount of the reducing agent with respect to the total amount of magnetic metals is 3.5 or more and 10.0 or less in terms of molar ratio. Is preferable, and 4.5 or more and 9.0 or less are more preferable. On the other hand, in the case of producing iron-nickel-cobalt alloy powder, the amount of the reducing agent compounded can be significantly reduced as compared with the iron-nickel alloy powder due to the action of the water-soluble cobalt salt described above. In particular, the action of the water-soluble cobalt salt is remarkable in the production of alloy powder having a large iron content. For example, when an alloy powder having an iron content of 60 mol% or more and 85 mol% or less and a cobalt (Co) content of 10 mol% or more and 30 mol% or less is produced, the total amount of magnetic metals is produced. The blending amount of the reducing agent with respect to the above is preferably 1.0 or more and 4.0 or less in terms of molar ratio, and more preferably 1.2 or more and 2.0 or less.

In any case, when the blending amount is equal to or higher than the above-mentioned lower limit, the reduction of magnetic metal ions and complex ions proceeds sufficiently, and crystallization powder (alloy powder) without contamination of unreduced substances such as iron hydroxide. Can be obtained. Further, when the blending amount is not more than the above-mentioned upper limit value, the amount of the reducing agent (hydrazine) used can be suppressed, which leads to a reduction in manufacturing cost.

(E) pH adjuster The pH adjuster is an alkali hydroxide. This pH adjuster (alkali hydroxide) has the effect of strengthening the reduction reaction of hydrazine, which is a reducing agent. That is, the higher the pH of the reaction solution, the stronger the reducing power of hydrazine. Therefore, the use of alkali hydroxide as the pH adjuster promotes the reduction reaction of magnetic metal ions and complex ions in the reaction solution and the accompanying precipitation of crystallization powder. The type of alkali hydroxide is not particularly limited. However, in terms of availability and price, it is preferred that the pH regulator comprises at least one selected from sodium hydroxide (NaOH) and potassium hydroxide (KOH).

The blending amount of the pH adjuster (alkali hydroxide) may be adjusted so that the reducing power of the reducing agent (hydrazine) is sufficiently high. Specifically, the pH of the reaction solution at the reaction temperature is preferably 9.5 or more, more preferably 10 or more, still more preferably 10.5 or more. Therefore, the blending amount of alkali hydroxide may be adjusted so that the pH is within this range.

(F) Amine compound If necessary, the starting material may further contain an amine compound. This amine compound may have two or more primary amino groups (-NH ₂ ), one primary amino group (-NH ₂ ) and one or more secondary amino groups (-NH-), or It contains two or more secondary amino groups (-NH-) in the molecule.

The amine compound has an action of accelerating the reduction reaction in the subsequent crystallization step. That is, the amine compound has a function as a complexing agent, and has a function of complexing magnetic metal ions (Fe ²⁺ , Ni ²⁺ , etc.) in the reaction solution to form complex ions (Fe complex ion, Ni complex ion, etc.). There is. As a result of the presence of complex ions in the reaction solution, it is considered that the reduction reaction further proceeds.

In addition, the amine compound has an effect of suppressing autolysis of hydrazine, which is a reducing agent. That is, when crystallization powder made of a magnetic metal is deposited in the reaction solution, nickel (Ni) in the magnetic metal acts as a catalyst, and as a result, hydrazine may be decomposed. This is called hydrazine autolysis. This decomposition reaction is a reaction in which hydrazine (N ₂ H ₄ ) is decomposed into nitrogen (N ₂ ) and ammonia (NH ₃ ) as shown in the following formula (1). When such autolysis occurs, the function of hydrazine as a reducing agent is impaired, which is not preferable.

By adding the amine compound to the compounding solution, it becomes possible to suppress the autolysis of hydrazine. The detailed mechanism is unknown, but it is speculated that it may be because the excessive contact between hydrazine and the crystallization powder in the reaction solution is hindered. That is, among the amino groups contained in the amine compound molecule, particularly the primary amino group (-NH ₂ ) and the secondary amino group (-NH-) are strongly adsorbed on the surface of the crystallization powder in the reaction solution. It is believed that the amine compound molecule covering and protecting the crystallization powder prevents excessive contact between the hydrazine molecule and the crystallization powder, thereby suppressing the autolysis of hydrazine. Since the autolysis of hydrazine becomes remarkable when the content of nickel in the magnetic metal is large, the amine compound works effectively especially in such a case.

The amine compound is preferably at least one of an alkylene amine and an alkylene amine derivative. Further, the alkyleneamine and / or the alkyleneamine derivative preferably has at least the structure represented by the following (A) in which the nitrogen atom of the amino group in the molecule is bonded via a carbon chain having 2 carbon atoms.

By using such an alkylene amine or an alkylene amine derivative as an amine compound, the effect of suppressing autolysis of hydrazine (reducing agent) can be exhibited even more effectively. It is considered that the reason is that such alkyleneamines and alkyleneamine derivatives effectively suppress the contact of hydrazine molecules with the crystallization powder because the carbon chains contained therein are short. On the other hand, when the nitrogen atom of the amino group is bonded via an excessively long carbon chain, the degree of freedom of movement of the carbon chain is large even if the amino group is adsorbed on the crystallization powder. Therefore, it is speculated that the contact between the crystallization powder and the hydrazine molecule may not be effectively hindered.

Specific examples of the alkylene amine having the structure represented by (A) above include ethylenediamine (abbreviation: EDA) (H ₂ NC ₂ H ₄ NH ₂ ) and diethylenetriamine (abbreviation: DETA) (H ₂ NC ₂ H ₄ NHC ₂ ). H ₄ NH ₂ ), triethylenetetramine (abbreviation: TETA) (H ₂ N (C ₂ H ₄ NH) ₂ C ₂ H ₄ NH ₂ ), tetraethylenepentamine (abbreviation: TEPA) (H ₂ N (C ₂ ) H ₄ NH) ₃ C ₂ H ₄ NH ₂ ), pentaethylenehexamine (abbreviation: PEHA) (H ₂ N (C ₂ H ₄ NH) ₄ C ₂ H ₄ NH ₂ ), propylenediamine (other names: 1, 2) -Diaminopropane, 1,2-propanediamine) (abbreviation: PDA) (CH ₃ CH (NH ₂ ) CH ₂ NH ₂ ) is one or more selected from the group. Specific examples of the alkyleneamine derivative having the structure represented by (A) above include tris (2-aminoethyl) amine (abbreviation: TAEA) (N (C ₂ H ₄ NH ₂ ) ₃ ), N- (2). -Aminoethyl) Ethanolamine (Alternative name: 2- (2-Aminoethylamino) Ethanol (abbreviation: AEEA) (H ₂ NC ₂ H ₄ NHC ₂ H ₄ OH), N- (2-Aminoethyl) propanolamine ( Another name: 2- (2-aminoethylamino) propanol (abbreviation: AEPA) (H ₂ NC ₂ H ₄ NHC ₃ H ₆ OH), L (or D, DL) -2,3-diaminopropionic acid (separately) Name: 3-amino-L (or D, DL) -alanine) (abbreviation: DAPA) (H ₂ NCH ₂ CH (NH) COOH), ethylenediamine-N, N'-diacetic acid (other name: ethylene-N) , N'-diglycine) (abbreviation: EDDA) (HOOCCH ₂ NHC ₂ H ₄ NHCH ₂ COOH), 1,2-cyclohexanediamine (also known as 1,2-diaminocyclohexane) (abbreviation: CHDA) (H ₂ NC ₆ ) One or more selected from H ₁₀ NH ₂ ). These alkylene amines and alkylene amine derivatives are water-soluble, and among them, ethylenediamine and diethylenetriamine have a relatively strong self-decomposition inhibitory effect on hydrazine and are easily available. It is preferable because it is inexpensive and inexpensive.

Ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), propylenediamine (PDA), tris (2-aminoethyl) amine (TAEA), Structure of N- (2-aminoethyl) ethanolamine (AEEA), N- (2-aminoethyl) propanolamine (AEPA), and L (or D, DL) -2,3-diaminopropionic acid (DAPA) The formula is shown in the following (B) to (M).

The blending amount of the amine compound with respect to the total amount of the magnetic metal is preferably 0.00 mol% or more and 5.00 mol% or less, more preferably 0.01 mol% or more and 5.00 mol% or less, and 0.03 mol% or more and 5 More preferably, it is 0.00 mol% or less. The blending amount of the amine compound is 0.00 mol%, that is, the amine compound may not be blended. However, when the blending amount is 0.01 mol% or more, the effect of suppressing the autolysis of hydrazine based on the amine compound and the effect of promoting the reduction reaction can be fully exerted. Further, by setting the blending amount to 5.00 mol% or less, the function as a complexing agent can be appropriately expressed. Therefore, it becomes possible to improve the powder characteristics (particle size, particle size distribution, spheroidity, surface texture of particles) of the alloy powder. When the blending amount of the amine compound exceeds 5.00 mol%, the function as a complexing agent becomes too strong. There is a risk that the particle growth will be abnormal and the powder properties of the alloy powder will deteriorate.

<Crystalization process>
In the crystallization step, a reaction solution containing the prepared starting material and water is prepared, and the crystallization powder containing the magnetic metal is crystallized in this reaction solution by a reduction reaction. The preparation of the reaction solution and the crystallization of the crystallization powder will be described below. In the actual production, in most cases, the crystallization reaction starts at the same time as the reaction solution is prepared, but there is a possibility that the crystallization reaction starts even slightly during the preparation of the reaction solution. The crystallization reaction referred to here is a reaction that occurs in the crystallization process. That is, although the reduction reaction with hydrazine (formula (6) described later) is the main, the autolysis reaction of hydrazine (formula (1) described above) is also included. Therefore, the term crystallization reaction is used in a broader sense than the reduction reaction.

In the crystallization step, at least one of a plurality of solutions such as a metal salt raw material solution and a reducing agent solution is heated and then mixed to prepare a reaction solution, and the reaction solution is heated and stirred in a reaction vessel to a predetermined temperature. Keep it and proceed with the crystallization reaction in that state. A general-purpose method can be applied to heating, and examples thereof include a method in which a reaction vessel (reaction vessel) is installed in a water bath, or a reaction vessel with a steam jacket or a reaction vessel with a heater is used. The reaction vessel (reaction vessel) and the stirring blade for stirring the reaction solution are made of an inert material that does not easily generate nuclei on their surfaces when in contact with the reaction solution from the viewpoint of not interfering with the action of the nucleating agent. In addition, it is required to have excellent strength and thermal conductivity. In order to satisfy these, for example, a metal container coated with a fluororesin (PTFE, PFA, etc.) (Teflon (registered trademark) -coated stainless steel container, etc.) or a stirring blade (Teflon (registered trademark) -coated stainless steel stirring blade, etc.) is suitable. Is.

(A) Preparation of reaction solution First, a magnetic metal source, a nucleating agent, a complexing agent, a reducing agent, a pH adjuster, and if necessary, an amine compound, which are starting materials, are dissolved in water and then mixed. Then, the reaction solution can be prepared. As the water used for preparing this reaction solution, it is preferable to use a highly pure water in order to reduce the amount of impurities in the finally obtained alloy powder. As high-purity water, pure water having a conductivity of 1 μS / cm or less and ultrapure water having a conductivity of 0.06 μS / cm or less can be used, and among them, pure water which is inexpensive and easily available. It is preferable to use.

When the starting material is a solid such as iron salt, nickel salt, cobalt salt, alkali hydroxide, etc., it is preferable to mix and dissolve them in advance with water to make an aqueous solution. The starting material and water may be mixed by a known method such as stirring and mixing. The procedure for mixing the starting material and the aqueous solution is not particularly limited as long as the uniformity of the reaction solution is not impaired. However, from the viewpoint of ensuring the uniformity of the reaction solution, it is preferable to separately prepare an aqueous solution containing each starting material in advance and mix the prepared aqueous solution, and the first aspect or the second aspect described below is used. Therefore, it is particularly preferable to prepare a reaction solution.

In the first aspect, when preparing a reaction solution in the crystallization step, a metal salt raw material solution in which a magnetic metal source, a nucleating agent, and a complexing agent are dissolved in water, and a reducing agent in which a reducing agent is dissolved in water are used. Prepare a solution and a pH-adjusting solution in which the pH-adjusting agent is dissolved in water, and mix the metal salt raw material solution and the pH-adjusting solution to form a mixed solution, and mix the obtained mixed solution and the reducing agent solution. do. 2 and 3 show a process diagram showing an example of reaction solution preparation and alloy powder production in the first aspect.

In the first aspect, three solutions of a metal salt raw material solution, a reducing agent solution and a pH adjusting solution are prepared separately. The metal salt raw material solution dissolves a magnetic metal source (water-soluble iron salt, water-soluble nickel salt, etc.), a nucleating agent (water-soluble salt of a metal nobler than nickel), and a complexing agent (hydroxycarboxylic acid, etc.) in water. To prepare. The reducing agent solution is prepared by dissolving the reducing agent (hydrazine) in water. The pH adjusting solution is prepared by dissolving a pH adjusting agent (alkali hydroxide) in water. Then, the metal salt raw material solution and the pH adjustment solution are mixed to prepare a mixed solution. At this time, the magnetic metal salt (water-soluble iron salt, water-soluble nickel salt, etc.) contained in the metal salt raw material solution reacts with the alkali hydroxide contained in the pH adjuster to form a magnetic metal hydroxide. Will be done. This hydroxide is iron hydroxide (Fe (OH) ₂ ), nickel hydroxide (Ni (OH) ₂ ), cobalt hydroxide (Co (OH) ₂ ), iron nickel hydroxide ((Fe, Ni)). (OH) ₂ ), iron nickel cobalt hydroxide ((Fe, Ni, Co) (OH) ₂ ) and the like. Then, the reducing agent solution is mixed with the obtained mixed solution to prepare a reaction solution.

As a specific procedure for preparing the reaction solution in the first aspect, it is preferable to sequentially add a pH adjusting solution and a reducing agent solution to the metal salt raw material solution and mix them. In the first aspect using three kinds of solutions, a metal salt raw material solution, a reducing agent solution, and a pH adjusting solution, the metal salt raw material solution has the largest amount (volume). Therefore, it is possible to realize a uniform mixed state by sequentially adding other solutions to the metal salt raw material solution having a large amount of liquid and mixing them, as compared with adding the metal salt raw material solution to the other solutions, and it is uniform in the reaction solution. This is because the reduction reaction can proceed.

When blending an amine compound, the amine compound may be added to at least one of the metal salt raw material solution, the reducing agent solution and the pH adjuster solution. Further, the amine compound may be added after mixing all of these solutions. FIG. 2 shows an embodiment in which an amine compound is added to at least one of a metal salt raw material solution, a reducing agent solution, and a pH adjusting solution. FIG. 3 shows an embodiment in which an amine compound is added to a reaction solution obtained by mixing all of a metal salt raw material solution, a reducing agent solution and a pH adjusting solution.

In the first aspect, a reducing agent solution is mixed with a mixed solution of a metal salt raw material solution and a pH adjuster to prepare a reaction solution, and the reduction reaction proceeds from the time when the reducing agent solution is added. When the reducing agent solution is mixed, the concentration of the reducing agent (hydrazine) rises locally in the minute region where the reducing agent is added. Further, the mixed solution contains a pH adjuster (alkali hydroxide), and the pH of the mixed solution (reaction solution) is still high at the initial stage of mixing the reducing agent solution with the mixed solution. As described above, the higher the pH, the stronger the reducing agent (hydrazine) exerts its reducing power. Therefore, in the initial stage of mixing the reducing agent solution, the concentration and pH of the reducing agent are locally increased, and the nucleation caused by the nucleating agent and the reduction reaction for producing crystallization powder occur rapidly. On the other hand, as the reducing agent solution is added, the pH of the mixed solution (reaction solution) gradually decreases. Therefore, at the final stage of mixing the reducing agent solution, the reducing power of the reducing agent is not as strong as at the initial stage, and the nucleation and the reduction reaction proceed slowly. Therefore, there is a difference in the reducing power of the reducing agent between the initial stage and the final stage of the reduction solution mixing.

If the difference in reducing power between the initial stage and the final stage is large, the uniformity of the nucleation reaction and the reduction reaction decreases, and the powder characteristics (particle size, surface smoothness, etc.) of the obtained crystallization powder increase. There is a fear. Therefore, it is desirable to reduce the difference in reducing power as much as possible. For that purpose, it is preferable to mix the reducing agent solution as quickly as possible. The time (mixing time) required to mix the reducing agent solution with the mixed solution of the metal salt raw material solution and the pH adjuster is preferably 180 seconds or less, more preferably 120 seconds or less, still more preferably 60 seconds or less. On the other hand, it may be difficult to make the mixing time excessively short due to the restrictions of the manufacturing equipment. The mixing time may be 1 second or longer, 3 seconds or longer, or 5 seconds or longer.

Even when the pH adjuster solution is mixed with the metal salt raw material solution, if the mixing time is long, the characteristics of the formed magnetic metal hydroxide may vary, which may lead to variations in the powder characteristics of the crystallization powder. There is. The effect is not as great as when mixing the reducing agent solution, but shorter mixing times are preferred. The time (mixing time) required to mix the pH adjuster is preferably 180 seconds or less, more preferably 120 seconds or less, still more preferably 80 seconds or less. The mixing time may be 1 second or longer, 3 seconds or longer, or 5 seconds or longer.

In order to suppress variations in the powder characteristics of the crystallization powder, it is also effective to perform stirring mixing in which the reducing agent solution and the pH adjusting agent solution are mixed while stirring the solutions. By stirring, a rapid increase in the concentration of components in the solution can be suppressed, so that it becomes possible to suppress variations in the characteristics of the crystallization powder. The stirring and mixing may be performed using a stirring device such as a stirring blade.

In the second aspect, when preparing the reaction solution in the crystallization step, a metal salt raw material solution in which a magnetic metal source, a nucleating agent, and a complexing agent are dissolved in water, and a reducing agent and a pH adjusting agent are dissolved in water. Prepare the prepared reducing agent solution and the metal salt raw material solution and the reducing agent solution, respectively. 4 and 5 show a process diagram showing an example of reaction solution preparation and alloy powder production in the second aspect.

In the second aspect, two solutions, a metal salt raw material solution and a reducing agent solution, are prepared separately. The metal salt raw material solution contains a magnetic metal source (water-soluble iron salt, water-soluble nickel salt, etc.), a nucleating agent (water-soluble salt of a metal nobler than nickel), and a complexing agent (hydroxycarboxylic acid, etc.) in water. Prepare by dissolving. The reducing agent solution is prepared by dissolving the reducing agent (hydrazine) and the pH adjuster (alkali hydroxide) in water. Next, the metal source raw material solution and the reducing agent solution are mixed to prepare a reaction solution. The second aspect differs from the first aspect in that the reducing agent solution contains a pH adjuster.

As a specific procedure for preparing the reaction solution in the second aspect, the reducing agent solution is added to the metal salt raw material solution and mixed, or conversely, the metal salt raw material solution is added to the reducing agent solution and mixed. There are two possible ways to do this. Unlike the first aspect, the liquid amount (volume) of the reducing agent solution containing both the reducing agent and the pH adjuster (alkali hydroxide) is at the same level as the liquid amount (volume) of the metal salt raw material solution. Therefore, by adding one of them to the other and mixing them, a uniform mixed state can be basically realized, and a uniform reduction reaction can be promoted in the reaction solution.

However, in the case of crystallization conditions in which the mixing ratio of the reducing agent or pH adjuster (alkali hydroxide) to the metal salt raw material is large, it is preferable to add the metal salt raw material solution to the reducing agent solution and mix them. This is because it is desired that the concentration of the metal salt raw material in the reaction solution be maintained at a predetermined level or higher (30 to 40 g / L for the metal component) from the viewpoint of ensuring the productivity of the crystallization step. That is, under the above-mentioned crystallization conditions, the liquid amount (volume) of the reducing agent solution is considerably larger than the liquid amount (volume) of the metal salt raw material solution. Therefore, it is better to add a metal salt raw material solution having a small amount (volume) to a reducing agent solution having a large amount (volume) and mix them to achieve a uniform mixed state, and a uniform reduction reaction in the reaction solution. Can be advanced.

Also in the second aspect, for the same reason as in the first aspect, the time (mixing time) required to mix the reducing agent solution with the metal salt solution is preferably 180 seconds or less, more preferably 120 seconds or less, and more preferably 60 seconds. The following is more preferable. The mixing time may be 1 second or longer, 3 seconds or longer, or 5 seconds or longer. It is also effective to stir and mix when mixing the reducing agent solution.

In the third aspect, in the crystallization steps of the first aspect and the second aspect, an additional raw material solution is further added and mixed with the reaction solution before the reduction reaction is completed. This makes the surface of the crystallization powder rich in nickel and cobalt components. Here, the additional raw material liquid is obtained by dissolving at least one of the above-mentioned water-soluble nickel salt and water-soluble cobalt salt in water. A process diagram showing an example of alloy powder production in the third aspect is shown in FIG.

In the third aspect, an additional raw material solution is prepared in addition to the solution used for preparing the reaction solution of the first aspect and the second aspect. This additional raw material liquid is prepared by dissolving at least one of a water-soluble nickel salt and a water-soluble cobalt salt in water. The additional raw material liquid may be added to the reaction liquid by a method such as batch addition, divided addition, and / or dropping. The addition is not inevitable, but is preferably performed at a timing before the reduction reaction is completed. When the reduction reaction is completely completed, the crystallized particles begin to form aggregates. If the additional raw material liquid is added at this timing to promote the precipitation of the metal component by the reduction reaction, the bonds between the particles contained in the aggregate may be strengthened.

Further, according to the third aspect, there is an advantage that the amount of the reducing agent used can be reduced as compared with the first aspect and the second aspect. Iron ion (or iron hydroxide) is less likely to be reduced than nickel ion (or nickel hydroxide) or cobalt ion (or cobalt hydroxide). This is because if an additional raw material solution containing a nickel component or a cobalt component is added to the reaction solution, the reduction reaction of iron ions (or iron hydroxide), which are difficult to reduce, can be promoted at the final stage of crystallization.

The amount of magnetic metal (Ni, Co) in the additional raw material liquid may be set according to the degree to which the surface of the crystallization powder is rich in nickel and cobalt components. However, considering the composition uniformity of the entire particles, it is preferably 5 mol% to 50 mol% with respect to the total amount of magnetic metals (Ni, Co) excluding iron in the alloy powder. When the particle surface becomes rich in nickel and cobalt components, the iron component that tends to form a porous oxide film decreases. Therefore, a dense oxide film is formed and the amount of oxidation on the particle surface is suppressed, so that not only is it more stable in the atmosphere, but also magnetic characteristics such as saturation magnetic flux density are improved.

(B) When a crystallization reaction solution of crystallization powder is prepared, a reduction reaction occurs in this reaction solution. That is, in the coexistence of a pH adjuster (alkali hydroxide) and a nucleating agent (a salt of a metal nobler than nickel), the ions and complex ions of the magnetic metal source are reduced by the reducing agent (hydrazine), thereby containing the magnetic metal. Crystallized powder is formed.

The reduction reaction in the crystallization step will be described using a reaction formula. The reduction reaction of iron (Fe), nickel (Ni) and cobalt (Co) is a two-electron reaction as shown in the following equations (2) to (4). On the other hand, the reaction of hydrazine (N ₂ H ₄ ) as a reducing agent is a 4-electron reaction as shown in the following formula (5).

When magnetic metal chlorides (FeCl ₂ , NiCl ₂ , CoCl ₂ ) are used as the magnetic metal source and sodium hydroxide (NaOH) is used as the pH adjuster, first, as shown in the following formula (6), first. The magnetic metal chloride and sodium hydroxide undergo a neutralization reaction to produce hydroxides ((Fe, Ni, Co) (OH) ₂ , etc.). Then, this hydroxide ((Fe, Ni, Co) (OH) ₂ , etc.) is reduced by the action of the reducing agent (hydrazine) to become crystallization powder. In order to reduce 1 mol of magnetic metal (Fe, Ni, Co), 0.5 mol of reducing agent (hydrazine) is required. Further, as can be seen from the above equation (5), the higher the alkalinity (pH), the higher the reducing power of hydrazine. Therefore, sodium hydroxide used as a pH adjuster also has an effect of accelerating the reduction reaction by hydrazine.

In the reduction reaction of the above formula (6), the reduction of ions (or hydroxides) of each element of the magnetic metal (Fe, Ni, Co) proceeds simultaneously to some extent by co-reduction. Here, the co-reduction refers to a phenomenon in which when a reduction reaction of a certain element occurs, another reduction reaction occurs concomitantly. However, as described above, iron ion (or iron hydroxide) is less likely to be reduced than nickel ion (or nickel hydroxide) or cobalt ion (or cobalt hydroxide). Therefore, at the end of the crystallization reaction, nickel ions (or nickel hydroxide) and cobalt ions (or cobalt hydroxide) are consumed and disappear in the reduction reaction, and iron ions (or iron hydroxide) remain. Tend to do. This tendency is particularly remarkable when the iron content is high (for example, the iron content of the alloy powder is more than 60 mol%). When such a phenomenon occurs, not only does it take a long time to complete the crystallization reaction (reduction reaction), but also an inclined structure having a non-uniform composition is likely to be formed in the particles. When the inclined structure is formed, the particle center of the obtained alloy powder has a rich composition of nickel and cobalt, and the closer to the particle surface, the richer the composition of iron.

On the other hand, in the third aspect described above, an additional raw material solution is added to the reaction solution during the crystallization reaction to promote the reduction reaction of iron ions (or iron hydroxide) that are difficult to reduce at the final stage of crystallization. are doing. Therefore, it is possible to improve the crystallization reaction (reduction reaction) for a long time, especially when the iron content ratio is large, and the composition non-uniformity in the obtained alloy powder particles.

The temperature of the reaction solution at the start of crystallization of the crystallization powder (reaction start temperature) is preferably 40 ° C. or higher and 90 ° C. or lower, more preferably 50 ° C. or higher and 80 ° C. or lower, and further preferably 60 ° C. or higher and 70 ° C. or lower. Here, the reaction solution at the start of crystallization is a reaction solution containing water and a starting material immediately after preparation. The temperature of the reaction solution held during crystallization after the start of crystallization (reaction holding temperature) is preferably 60 ° C. or higher and 99 ° C. or lower, more preferably 70 ° C. or higher and 95 ° C. or lower, and 80 ° C. or higher and 90 ° C. or lower. More preferred. In order to adjust the reaction start temperature within a suitable range, it is desirable to preheat at least one of a plurality of solutions such as a metal salt raw material solution and a reducing agent solution used for preparing the reaction solution. In order to adjust the reaction holding temperature within a suitable range, it is desirable to continue heating the reaction solution after preparing the reaction solution.

If possible, preheat one of a plurality of solutions such as a metal salt raw material solution and a reducing agent solution (for example, 70 ° C.) from the viewpoint of making nucleation more uniform and obtaining crystallization powder having a sharp particle size distribution. It is preferable to prepare a reaction solution having a predetermined temperature (for example, 55 ° C.) by adding and mixing them without heating the other solution in advance (for example, keeping it at 25 ° C.). On the other hand, if both of the two solutions (for example, the metal salt raw material solution and the reducing agent solution) are preheated (for example, heated to 70 ° C.), non-uniform nucleation is likely to occur. That is, when two solutions are added and mixed, heat generation of mixing of the solutions occurs. Therefore, the added and mixed solution (reaction solution) becomes locally high temperature (for example, about 78 ° C.) at the start of mixing, and nuclear generation occurs instantaneously. While nucleation occurs, the two solutions are added and mixed, and this state tends to cause non-uniformity of nucleation.

Although it is conceivable to improve the uniformity of nuclear generation by a method such as extremely shortening the addition time of the two solutions or vigorously stirring, such a method is not always a preferable embodiment. In the method described above in which only one of the solutions is preheated (for example, heated to 70 ° C.) and then added and mixed to prepare a reaction solution, the added and mixed solution (reaction solution) is maintained at a low temperature (for example, 55 ° C.). , It does not get hot locally. Since the timing of nucleation is delayed, nucleation proceeds after the two solutions are well mixed. Therefore, nuclear generation is likely to occur uniformly. The above describes more preferable examples, and does not exclude the case where all of a plurality of solutions such as a metal salt raw material solution and a reducing agent solution are preheated. The solution may be heated and its temperature may be set so that the reaction start temperature and the reaction holding temperature fall within the above-mentioned ranges.

If the reaction start temperature is excessively low, the nuclear generation becomes more uniform, but the progress of the reduction reaction is slow, and the heating time required for raising the temperature to the reaction holding temperature at which the reduction reaction can be promoted becomes long. Similarly, if the reaction holding temperature is excessively low, the progress of the reduction reaction is slow and the heating time required for crystallization becomes long. In either case, the cycle time required in the crystallization step becomes long and the productivity decreases. Moreover, as the autolysis of hydrazine progresses, a large amount of hydrazine is required, resulting in an increase in manufacturing cost. When the reaction start temperature and the reaction holding temperature are high, the reduction reaction is promoted, the cycle time required in the crystallization step is shortened, and the obtained crystallization powder tends to be highly crystallized. However, at the same time, the autolysis rate of hydrazine increases. Therefore, if the reaction start temperature or reaction holding temperature is excessively high, not only non-uniformity of nucleation occurs, but also excessive high crystallization may deteriorate the smoothness of the particle surface and increase the surface irregularities. There is. If crystallization is not completed at an appropriate timing, hydrazine may be autolyzed and preferentially consumed by the reduction reaction. Therefore, a large amount of hydrazine is required, and there is a concern that the manufacturing cost will increase. By setting the reaction start temperature and the reaction holding temperature within the above-mentioned suitable ranges, it becomes possible to inexpensively produce high-performance alloy powder while maintaining high productivity.

<Recovery process>
In the recovery step, the crystallization powder is recovered from the reaction solution obtained in the crystallization step. The crystallization powder may be recovered by a known method. For example, a method of solid-liquid separation of crystallized powder from a reaction solution using a separation device such as a Denver filter, a filter press, a centrifuge, or a decanter can be mentioned. Further, the crystallization powder may be washed at the time of solid-liquid separation or after solid-liquid separation. Cleaning may be performed using a cleaning liquid. High-purity pure water having a conductivity of 1 μS / cm or less may be used as the cleaning liquid. The crystallization powder after washing may be subjected to a drying treatment. The drying treatment is performed using a general-purpose drying device such as an air dryer, a hot air dryer, an inert gas atmosphere dryer, a reducing gas atmosphere dryer, or a vacuum dryer, and the temperature is 40 ° C or higher and 150 ° C or lower, preferably 50. It may be carried out at a temperature of ° C. or higher and 120 ° C. or lower. However, from the viewpoint of preventing deterioration of magnetic properties due to excessive oxidation of the crystallization powder during the drying process, an inert gas atmosphere dryer and a reducing gas atmosphere dryer are used rather than an air dryer or a hot air dryer using the air. It is preferable to use a machine or a vacuum dryer.

The particle surface of the crystallization powder dried in the closed container of the inert gas atmosphere dryer, the reducing gas atmosphere dryer, or the vacuum dryer is not so much oxidized. Therefore, if the particles are taken out of the dryer into the atmosphere immediately after drying, the surface of the particles is rapidly oxidized, and the heat generated by the oxidation reaction may cause the crystallization powder to burn. This phenomenon is particularly likely to occur with fine crystallization powder (for example, a particle size of 0.1 μm or less). Therefore, it is desirable to perform a slow oxidation treatment to stabilize the particle surface of the crystallization powder by forming a thin oxide film in advance on the particle surface of the crystallization powder whose surface is not so oxidized after drying. As a specific procedure for the slow oxidation treatment, the temperature of the crystallization powder heated and dried in the closed container of the inert gas atmosphere dryer, the reducing gas atmosphere dryer, or the vacuum dryer is set to about room temperature to 40 ° C. After lowering, a gas with a low oxygen concentration (for example, nitrogen gas or argon gas containing 0.1 to 2% by volume of oxygen) is supplied into the closed container to slowly and slowly oxidize the particle surface of the crystallization powder. A method of forming a thin oxide film can be considered. Since the crystallization powder that has been subjected to the slow oxidation treatment is not easily oxidized and is stable, there is no risk of heat generation or combustion even if it is left in the atmosphere.

<High temperature heat treatment process>
After the recovery step or in the middle of the recovery step, a high temperature heat treatment step of applying a high temperature heat treatment to the crystallization powder may be provided. When the high temperature heat treatment is performed after the recovery step, the high temperature heat treatment may be performed after the drying treatment. When high temperature heat treatment is performed in the middle of the recovery process, high temperature heat treatment may be performed instead of the drying treatment. The high temperature heat treatment may be performed in an inert atmosphere, a reducing atmosphere, or a vacuum atmosphere at a temperature of more than 150 ° C. and 400 ° C. or lower, preferably 200 ° C. or higher and 350 ° C. or lower. High-temperature heat treatment promotes diffusion of dissimilar elements such as Fe and Ni in iron (Fe) -nickel (Ni) alloy particles to improve composition uniformity in the particles, or adjust magnetic properties such as magnetic force. It is possible to do it. If necessary, the above-mentioned slow oxidation treatment may be performed after the high temperature heat treatment.

<Crushing process>
If necessary, a crushing step may be provided in which the crystallization powder recovered in the recovery step or the crystallization powder before the drying treatment is crushed during the recovery process. When the alloy particles constituting the crystallization powder are deposited in the crystallization step, the alloy particles may come into contact with each other and fuse to form aggregated particles. Therefore, the crystallization powder obtained through the crystallization step may contain coarse agglomerated particles. As described above, coarse agglomerated particles may have eddy currents flowing through them to increase the loss due to Joule heat or hinder the filling property of the powder. Aggregated particles can be crushed by providing a crushing step after the recovery step or during the recovery step. The crushing may be performed by using dry crushing such as spiral jet crushing treatment and counter jet mill crushing treatment, wet crushing such as high-pressure fluid collision crushing treatment, and other general-purpose crushing methods. Dry crushing can be applied as it is to the crystallization powder that is the dry powder recovered in the recovery step. Further, if the crystallization powder, which is the dry powder after the recovery step, is made into a slurry, wet crushing can be applied to the slurry. Further, if it is a slurry-like crystallized powder before drying obtained in the middle of the recovery step, wet crushing can be applied as it is. In these crushing methods, agglomerated particles are crushed into pieces by utilizing the collision energy of the particles. Since the surface smoothing progresses due to collision during the crushing process, this effect also helps to improve the filling property of the powder.

<Insulation coating process>
If necessary, an insulating coating step may be provided after the recovery step. In the insulating coating step, the crystallization powder obtained through the recovery step is subjected to an insulating coating treatment to form an insulating coating layer made of a highly resistant metal oxide on the particle surface of the crystallization powder, thereby insulating the particles. Improve sex. Similar to the increase in loss due to eddy current in coarse agglomerated particles, in a dust core obtained by compression molding iron-nickel alloy powder, the eddy current flowing between the particles may increase due to contact between the alloy particles. By forming the insulating coat layer, it becomes possible to suppress the generation of eddy current due to the contact between the alloy particles.

In the insulation coating treatment, the crystallization powder is dispersed in a mixed solvent containing water and an organic solvent, and a metal alkoxide is further added and mixed with the mixed solvent to prepare a slurry, and the metal alkoxide is hydrolyzed and mixed in the obtained slurry. An insulating coat layer is formed on the surface of the particles of the crystallization powder by dehydration shrink polymerization, and then the cake-like crystallization powder on which the insulating coat layer is formed is solid-liquid separated from the slurry, and the separated crystallization powder is dried. The crystallization powder on which the insulating coat layer made of a highly resistant metal oxide is formed is recovered. If necessary, the separated and dried crystallization powder may be heat-treated. Since the hydrolysis reaction of metal alkoxide in a mixed solvent containing water and an organic solvent proceeds only very slowly as it is, generally, a small amount of a hydrolysis catalyst such as an acid or a base (alkali) is added. To promote the reaction. Also in this embodiment, it is preferable to add a base catalyst (alkaline catalyst).

The high resistance metal oxide is at least one selected from the group consisting of silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), and titanium dioxide (TIO ₂ ). Is preferable as the main component. In particular, those containing silicon dioxide (SiO ₂ ) as a main component are particularly preferable because they are inexpensive and have excellent insulating properties.

In order to obtain such a metal oxide, select an alkoxide capable of finally forming a metal oxide by hydrolysis and dehydration polycondensation as the metal alkoxide used for the slurry in the insulating coating treatment. Specifically, the main component is at least one selected from the group consisting of silicon alkoxide (alkyl silicate), aluminum alkoxide (alkyl alkoxide), zirconium alkoxide (alkyl zirconate), and titanium alkoxide (alkyl titanate). Those containing silicon alkoxide (alkyl silicate) as a main component are particularly preferable. If necessary, when the metal alkoxide is hydrolyzed and dehydrated and polycondensed to form an insulating coat layer, a component (for example, boron alkoxide or the like) that is incorporated into the insulating coat layer by hydrolysis or the like can be added. A small amount may be added to the above-mentioned metal alkoxide.

The surface of the alloy powder treated with insulation coating is coated with a high resistance metal oxide which is an inorganic substance. If necessary, an organic functional group may be introduced on the surface of the inorganic substance. Specifically, for example, a small amount of a silicon-based, titanium-based, zirconium-based, or aluminum-based coupling agent is blended with the metal alkoxide used in the insulating coating treatment, and the organic functional group is metallized during hydrolysis / dehydration shrink polymerization of the metal alkoxide. A method of incorporating into an oxide can be mentioned. Another method is to surface-treat the insulatingly coated alloy powder with the above-mentioned coupling agent to modify the surface of the metal oxide with an organic functional group. In either method, the introduction of an organic functional group enhances the affinity with the resin, so it is expected that the strength of the molded body will be improved when the alloy powder treated with an insulating coat is mixed with a resin binder or the like and molded. ..

Specific examples of silicon alkoxide (alkyl silicate) include, for example, tetramethoxysilane (other names: tetramethyl orthosilicate, silicon tetramethoxydo) (abbreviation: TMOS) (Si (OCH ₃ ) ₄ ), tetraethoxysilane (separate name). Name: Tetraethyl orthosilicate, silicon tetraethoxyoxide) (abbreviation: TEOS) (Si (OC _{2H 5} ₎ ₄ ), tetrapropoxysilane (other names: tetrapropyl orthosilicate, silicon tetrapropoxide) (Si (OC) ₃ H ₇ ) ₄ , tetrabutoxysilane (other names: tetrabutyl orthosilicate, and silicon tetrabutoxide) (Si (OC ₄ H ₉ ) ₄ and the like, and one or more selected from these alkoxide alkoxides. An alkoxide in which the group is substituted with another alkoxide group may be used, or a commercially available alkyl silicate as a silicate oligomer which has already been polymerized to a 4- to pentamer (for example, Elsilicate 40 (trade name) manufactured by Corcote, Inc., L. Silicate 48 (trade name), methyl silicate 51 (trade name), etc.) may be used. Among them, tetraethoxysilane (TEOS) is preferable because it is less harmful, easily available, and inexpensive.

Specific examples of aluminum alkoxide (alkyl aluminate) include, for example, aluminum trimethoxydo (Al (OCH ₃ ) ₃ ), aluminum triethoxydo (Al (OC ₂ H ₅ ) ₃ ), and aluminum triisopropoxide (Al (Al (OC 2 H 5) 3). O-iso-C ₃ H ₇ ) ₃ ), aluminum tri-n-butoxide (Al (On-C ₄ H ₉ ) ₃ ), aluminum tri-sec-butoxide (Al (O-s-C ₄ H ₉ )) ) ₃ ), one or more selected from aluminum tri-tert-butoxide (Al (Ot _- C 4H ₉ ) ₃ ) and the like.

Specific examples of zirconium alkoxide (alkyl zirconate) include, for example, zirconium tetraethoxyd (Zr (OC ₂ H ₅ ) ₄ ), zirconium tetra-n-propoxide (Zr (On-C ₃ H ₇ ) ₄ ). , Zirconium Tetraisopropoxide (Zr (O-iso-C _3H ₇ ) ₄ ), Zirconium Tetra-n-Butoxide (Zr ( _On -C 4H ₉ ) ₄ ), Zirconium Tetra-tert-Butoxide (Zr) (Ot-C ₄ H ₉ ) ₄ ), zirconium tetraisobutoxide (Zr (O-iso-C ₄ H ₉ ) ₄ ), and the like, and one or more selected from these can be mentioned.

Specific examples of titanium alkoxide (alkyl titanate) include, for example, titanium tetramethoxydo (Ti (OCH ₃ ) ₄ ), titanium tetraethoxydo (Ti (OC ₂ H ₅ ) ₄ ), and titanium tetraisopropoxide (Ti (O)). -Iso-C ₃ H ₇ ) ₄ ), Titanium Tetraisobutoxide (Ti (O-iso-C ₄ H ₉ ) ₄ ), Titanium Tetra-n-Butoxide (Ti (On-C ₄ H ₉ ) ₄ ) , Titanium tetra-tert-butoxide (Ti (Ot-C ₄ H ₉ ) ₄ ), Titanium tetra-sec-butoxide (Ti (O-s-C ₄ H ₉ ) ₄ ), etc. Can be mentioned.

Other metal alkoxides include boron alkoxides (alkyl boronates), such as boron trimethoxydo (B (OCH ₃ ) ₃ ), boron triethoxydo (B (OC ₂ H ₅ ) ₃ ), boron tri-tert-butoxide. (B (Ot-C ₄ H ₉ ) ₃ ) and the like can be mentioned as one or more selected.

The organic solvent used for the slurry in the insulating coating treatment is preferably one that forms a mixed solvent with water and is moderately easy to dry. That is, those having high compatibility with water and a relatively low boiling point (about 60 ° C to 90 ° C) are preferable. In addition, those that are highly safe, easy to handle, easy to obtain, and inexpensive are preferable. Considering these, a modified alcohol containing ethyl alcohol as a main component is preferable.

The hydrolysis reaction and dehydration-condensation polymerization reaction of the metal alkoxide in the insulation coating treatment will be described using a reaction formula when a silicon alkoxide (Si (OR) ₄ , R: alkyl group) is used as the metal alkoxide.

In the hydrolysis reaction, in the coexistence of a base catalyst (alkali catalyst) such as ammonia (NH ₃ ), the silicon atom (Si) is a pronuclear hydroxy ion (OH ⁻ ) as shown in the following equation (7). Under direct attack, one of the alkoxy groups (-OR) is first hydrolyzed. This reduces the charge on the silicon atom and makes it more vulnerable to the attack of pronuclear hydroxy ions (OH- ⁾ . As a result, as shown in the following formula (8), all four alkoxy groups (—OR) are hydrolyzed to silanol groups (Si—OH). As described above, when a base catalyst (alkali catalyst) is used, all the alkoxy groups (-OR) are hydrolyzed in the hydrolyzed silicon alkoxide molecule, so that the completely hydrolyzed molecule (Si (OH) ₄ ) is used. And a molecule (Si (OR) ₄ ) that has not been hydrolyzed at all coexists in the slurry.

On the other hand, in the coexistence of an acid catalyst such as nitric acid (HNO ₃ ), as shown in the following equation (9), the silicon atom (Si) becomes water (Si) due to the protonation of the alkoxy group (-OR) by the proton (H ⁺ ). It becomes vulnerable to _H2O ) attacks. Therefore, first, one of the alkoxy groups (-OR) is hydrolyzed to a silanol group (Si-OH). Details are omitted, but in this case, the charge on the silicon atom and the charge on the oxygen atom (O) are reduced, so that the attack of the proton (H ⁺ ) becomes less likely. Therefore, the next hydrolysis does not occur immediately, and the alkoxy group (−OR) of another unhydrolyzed silicon alkoxide molecule is more susceptible to hydrolysis. As described above, when the acid catalyst is used, the hydrolysis of the alkoxy group (−OR) proceeds evenly in all the silicon alkoxide molecules as shown in the following formula (10). Therefore, there is no completely hydrolyzed molecule or no hydrolyzed molecule at all, and the slurry is in a state where evenly hydrolyzed molecules (Si (OH) _X (OR) _4-X ; 0 <x <4) are present. Occurs inside.

In the dehydration-condensation polymerization reaction, as shown in the following formula (11), the formation of a siloxane bond (Si—O—Si) by the dehydration-condensation polymerization reaction of a silanol group (Si—OH) between hydrolyzed silicon alkoxide molecules is formed. This is an ongoing reaction, and when this dehydration-hydrolysis reaction proceeds and is completed, silicon dioxide (SiO ₂ ) is produced as shown in the following equation (12).

Summarizing the above, when the hydrolysis and dehydration polycondensation of silicon alkoxide are completed, silicon dioxide (SiO ₂ ) and alcohol are produced as shown in the following formula (13). For example, when tetraethoxysilane (TEOS: Si (OR) ₄ , R: C ₂ H ₅ ) is used, silicon dioxide (SiO ₂ ) and ethyl alcohol (C ₂ H ₅ OH) are produced.

The above equation (13) is established regardless of the base catalyst (alkali catalyst) or the acid catalyst as long as the silicon alkoxide is hydrolyzed, but the form of the nitrogen dioxide (SiO ₂ ) generated by the progress of dehydration-reduction polymerization. Is greatly affected by the state of hydrolysis by the above-mentioned hydrolysis catalyst.

In the silicon alkoxide molecule (Si (OH) _X (OR) _4-X ; 0 <x <4) uniformly hydrolyzed by an acid catalyst, an unhydrolyzed alkoxy group (-OR) is present in the molecule. Therefore, when the dehydration polycondensation of the silanol group (Si—OH) progresses between the molecules, a linearly or branched linearly polymerized hydrolyzed polymer is produced. When this occurs in the slurry in the insulating coating treatment, a hydrolyzed polymer of silicon alkoxide is produced on the surface of the particles composed of iron oxide (FeO) and nickel oxide (NiO) of the crystallization powder. However, since these are polymerized in a linear or branched linear shape, they are difficult to densify in the solvent of the slurry, and therefore it is not easy to form a dense insulating coat layer.

On the other hand, when a base catalyst (alkali catalyst) is used, a completely hydrolyzed molecule (Si (OH) ₄ ) is present. Therefore, when the dehydration polycondensation of the silanol group (Si—OH) progresses between the molecules, a dense hydrolyzed polymer polymerized in a lump is produced. Therefore, even in the solvent of the slurry in the insulating coating treatment, a dense hydrolyzed polymer of silicon alkoxide is produced on the particle surface composed of iron oxide (FeO) and nickel oxide (NiO) of the crystallization powder, and as a result, a dense hydrolyzed polymer of silicon alkoxide is produced. It is possible to form a dense insulating coat layer. When a base catalyst (alkali catalyst) is used, there is a possibility that a molecule (Si (OR) ₄ ) that has not been hydrolyzed at all may be present. However, as will be described later, a hydrolyzed polymer of completely unhydrolyzed molecules or particulate silicon alkoxide having a very small molecular weight that remains in the slurry without being consumed by the insulating coat of the crystallization powder in the insulating coating treatment. (Silica sol) is removed from the system together with the filtrate during the filtration cleaning in the insulating coating process. Therefore, it does not affect the insulating coating treatment.

For the above reasons, it is preferable to hydrolyze the metal alkoxide in the insulating coating treatment using a base catalyst (alkali catalyst) rather than an acid catalyst. In this respect, the preferred catalyst is different from the case where the solvent is applied to the substrate for coating. That is, when it is used as a binder for a coating liquid which is applied to a base material to dry the solvent instead of coating the particle surface in a solvent, the polymer is polymerized linearly or branched by the acid catalyst described above. Is preferable.

Regarding the timing of hydrolysis of metal alkoxide in the insulation coating treatment, the embodiment in which the crystallization powder and the metal alkoxide are uniformly mixed in the slurry and then hydrolyzed by the hydrolysis catalyst has been described so far. However, this embodiment is not limited to the mode of hydrolysis at this timing. For example, a metal oxide sol obtained by previously hydrolyzing a metal alkoxide with a hydrolysis catalyst (silica sol in the case of silicon alkoxide) may be prepared, and this metal oxide sol may be mixed with crystallization powder to form a slurry. It is possible. If the average molecular weight of the metal oxide sol is as small as about 500 to 5000, the timing of hydrolysis of the metal alkoxide has almost no effect. This is due to the bond between iron oxide (FeO) and nickel oxide (NiO) on the surface of the crystallization powder and the hydrolyzing group of the metal oxide sol (silanol group (Si-OH) in the case of silicon alkoxide). This is because the surface of the particles is covered with small metal oxide sol particles, and then the sol particles are polymerized with each other.

From the viewpoint of uniformly forming the insulating coat layer in the insulating coating treatment, the slurry containing crystallization powder, water, an organic solvent, a metal alkoxide, and a catalyst for hydrolysis can be agitated by a stirring blade using a stirrer. It is preferable to perform a treatment such as stirring by rotating the container using a dedicated roller. The treatment time and treatment temperature of the insulating coating treatment vary depending on the type of metal alkoxide applied and the required thickness of the insulating coating layer. For example, in general, metal methoxide has a higher rate of hydrolysis than metal ethoxide. Therefore, the processing time and the processing temperature may be set appropriately, and are not particularly limited. For example, the treatment time may be several hours to one week, and the treatment temperature may be room temperature to 60 ° C. When the treatment temperature is as high as 40 ° C. to 60 ° C., the treatment speed can be increased to several times that at room temperature.

The thickness of the insulating coat layer is not unconditionally limited because it depends on the degree of insulating property required. Speaking of which, 1 nm to 30 nm is preferable, 2 nm to 25 nm is more preferable, and 3 nm to 20 nm is further preferable. Even if it is excessively thick, the insulating property is saturated, but the content ratio of the soft magnetic component is lowered, and the magnetic characteristics such as the saturated magnetic flux density are only deteriorated. When the thickness is within the above range, it is possible to exert the insulating function of the insulating coat layer without significantly deteriorating the characteristics such as magnetic characteristics.

The crystallization powder on which the insulating coat layer was formed by hydrolysis and dehydration shrink polymerization of the metal alkoxide was made into a cake from the slurry by using a known separation device such as a Denver filter, a filter press, a centrifuge, or a decanter. It is solid-liquid separated as crystallization powder. If necessary, the crystallization powder may be washed at the time of solid-liquid separation or the like. For cleaning, water, an organic solvent such as alcohol having a relatively low boiling point, or a mixed solvent thereof may be used as a cleaning solution. As described above, if there is a metal alkoxide remaining in the slurry without being consumed by the insulating coat or a hydrolyzed polymer thereof (an unhydrolyzed molecule or a metal oxide sol having a small molecular weight), these are present. , It is removed from the system together with the filtrate and cleaning waste liquid during solid-liquid separation and cleaning.

The cake-shaped crystallization powder separated by solid and liquid is dried and, if necessary, heat-treated to recover the crystallization powder on which an insulating coat layer made of a highly resistant metal oxide is formed. Drying is not particularly limited as long as it can suppress excessive oxidation during drying. However, it is preferable to use a drying device such as an inert gas atmosphere dryer, a reducing gas atmosphere dryer, or a vacuum dryer, and the temperature may be 40 ° C. or higher and 150 ° C. or lower. The higher the drying temperature, the more the dehydration polycondensation of the metal alkoxide hydrolyzed polymer constituting the insulating coat layer progresses, and the metal oxide becomes harder, denser and more insulating. If further improvement is desired, the heat treatment may be performed in an inert gas atmosphere, a reducing gas atmosphere, or a vacuum at a temperature of more than 150 ° C and less than 450 ° C. Since the insulating coat layer has already been formed, it is basically unnecessary to perform a slow oxidation treatment after drying.

The insulating coating treatment greatly enhances the insulating property of the crystallization powder (alloy powder). For example, the resistivity of an iron-nickel alloy powder not coated with insulation (applied pressure: 64 MPa) is usually 0.1 Ω · cm or less, whereas the thickness of this iron-nickel alloy powder is 0.015 μm. When an insulating coating treatment for forming an insulating coating layer made of nickel dioxide (SiO ₂ ) of about (15 nm) is applied, the resistivity of the powder compact is improved to ¹⁰⁶ Ω · cm or more.

In this way, the iron (Fe) -nickel (Ni) -based alloy powder of the present embodiment can be produced. The production method of the present embodiment has the effects of promoting a reduction reaction, promoting spheroidization, and surface smoothing with a specific nucleating agent (a water-soluble salt of a metal nobler than nickel) having an effect of refining alloy powder. It is characterized by using a specific complexing agent (hydroxycarboxylic acid or the like), which makes it possible to improve the powder characteristics while maintaining the magnetic characteristics of the alloy powder after production. Specifically, the average particle size of the alloy powder after production can be freely controlled, and fine alloy powder can be obtained. Further, the obtained alloy powder has a narrow particle size distribution and a uniform particle size. Further, this alloy powder is spherical and its surface is smooth. Therefore, it is excellent in filling property. Further, although not limited, the amount of hydrazine used can be suppressed by using an amine compound having a function as an autolysis inhibitor of hydrazine and a reduction reaction accelerator. Therefore, it is possible to reduce the manufacturing cost and improve the powder characteristics of the alloy powder.

<< 2. Iron-nickel alloy powder >>
The iron (Fe) -nickel (Ni) alloy powder of the present embodiment has a small particle size distribution. Further, the average particle size of this alloy powder can be freely controlled. Therefore, miniaturization is easy and the particle size distribution can be reduced. In addition, it is spherical, has high surface smoothness, and has excellent filling properties. The alloy powder of the present embodiment having such an advantage can be used for various electronic components such as noise filters, choke coils, inductors, and radio wave absorbers, and is particularly compact for choke coils and inductors. Suitable as a core material.

The average particle size of the alloy powder is preferably 0.10 μm or more and 0.60 μm or less, and more preferably 0.10 μm or more and 0.50 μm or less. By appropriately increasing the average particle size, deterioration of magnetic properties and deterioration of filling property due to surface oxidation can be suppressed. Further, by appropriately reducing the average particle size, it is possible to suppress the eddy current loss.

The coefficient of variation (CV value) in the particle size distribution of the alloy powder is preferably 25% or less, more preferably 20% or less, and further preferably 15% or less. Here, the coefficient of variation is an index of particle size variation, and the smaller the coefficient of variation, the narrower the particle size distribution. By keeping the coefficient of variation small, the number of coarse particles and excessively fine particles with large surface oxidation is reduced, so that it is possible to prevent an increase in eddy current loss while maintaining excellent magnetic characteristics. The coefficient of variation (CV value) is calculated according to the following equation (14) by obtaining the average particle size and standard deviation in the number particle size distribution of the alloy powder.

The powder compact density of the alloy powder depends on the composition and particle size of the alloy powder. When the iron content is large, the specific gravity of the alloy is small, so that it decreases. It also tends to decline. Therefore, an iron-nickel alloy powder having an average particle size of 0.3 μm to 0.5 μm and an iron content of iron (Fe) of 45 mol% to 60 mol% having a specific gravity of 8.2 to 8.3. The powder density (applied pressure: 100 MPa) is preferably 3.60 g / cm ³ or more, and more preferably 3.70 g / cm ³ or more. Further, an iron-nickel alloy powder having an average particle size of 0.3 μm to 0.5 μm and an iron content ratio of iron (Fe) of 10 mol% to 20 mol% having a specific gravity of 7.9 to 8.0. In the case of, the powder compact density (applied pressure: 100 MPa) is preferably 3.45 g / cm ³ or more, and more preferably 3.55 g / cm ³ or more. Regarding the particle size of the alloy powder, when the average particle size is miniaturized from 0.3 μm to 0.5 μm to about 0.2 μm to 0.25 μm, the powder compact density (applied pressure: 100 MPa) is 0.1 g / g. About cm ³ tends to decrease. By increasing the powder compact density, it becomes possible to manufacture a powder compact core having excellent magnetic characteristics (magnetic flux density). The crystallite diameter of the alloy powder is preferably 30 nm or less, more preferably 10 nm or less. By keeping the crystallite diameter appropriately small, there is an effect that a small coercive force can be easily obtained as in the case of an amorphous soft magnetic material. The saturation magnetic flux density of the alloy powder is preferably 1 T (tesla) or more, more preferably 1.2 T or more, and even more preferably 1.5 T (tesla) or more. It is even more preferable if the saturation magnetic flux density of pure iron powder (1.95T to 2.0T) or higher. By increasing the saturation magnetic flux density of the alloy powder, the magnetic characteristics (magnetic flux density) of the dust core can be increased. The coercive force of the alloy powder is preferably 2000 A / m or less, more preferably 1600 A / m or less, and even more preferably 1200 A / m or less. By suppressing the coercive force of the alloy powder, it becomes possible to prevent an increase in hysteresis loss.

As mentioned above, iron ion (or iron hydroxide) is less likely to be reduced than nickel ion (or nickel hydroxide) or cobalt ion (or cobalt hydroxide), so iron (Fe) -nickel with a high iron content. In (Ni) -based alloy powder (for example, the iron content of the alloy powder exceeds 60 mol%), the central part of the particle has a rich composition of nickel and cobalt, and the closer to the particle surface, the richer the iron. , Core-shell structure) is likely to be formed in the particles. The composition tends to be non-uniform within the particles.

How the non-uniform composition in the particles affects the characteristics of the alloy powder, but it does not have a large effect on the magnetic characteristics (saturation magnetic flux density, coercive force, etc.). For example, the saturated magnetic flux density shows a positive correlation with the iron content (the higher the iron content, the higher the saturated magnetic flux density), so the composition becomes non-uniform in the particles and iron. Even if there is a region where the content ratio of the particles is larger than the average value and a region where the content ratio is smaller than the average value, there are regions where the saturation magnetic flux density is higher than the average value and smaller than the average value, and the average of the entire alloy powder is obtained. This is because the composition is almost the same as the case where the composition is uneven. Further, since the composition dependence of the iron-nickel (-cobalt) system is not so large in the iron-nickel (-cobalt) system, the holding power does not change significantly depending on the degree of non-uniformity of the composition that occurs in the particles.

On the other hand, the non-uniform composition in the particles may affect the chemical and physical characteristics such as oxidation resistance and coefficient of thermal expansion. As such an example, regarding the oxidation resistance, for example, if the particle surface has a more iron-rich composition due to the inclined structure, the oxidation may proceed easily and the oxidation resistance may deteriorate. If the particle surface can be modified to a nickel-rich composition according to the third aspect of the above, there is a possibility that the oxidation resistance can be improved. Next, regarding the coefficient of thermal expansion, unlike the case of the saturated magnetic flux density, the coefficient of thermal expansion of the iron-nickel alloy does not show a positive or negative correlation with the iron content, and the iron content is 65 mol%. It has the characteristic of becoming very small only in the vicinity of (64% by mass), and the low coefficient of thermal expansion alloy of this composition is called an Inver alloy (65 mol% of iron and 35 mol% of nickel are the main components). In the case of this composition, if the composition is non-uniform in the particles, the coefficient of thermal expansion does not decrease in either the region where the iron content is larger than 65 mol% or the region where the iron content is small. When Ni) -based alloy powder is used as Invar alloy powder, it is necessary to make the composition uniform by the above-mentioned high-temperature heat treatment or the like.

As far as the present inventors know, there is no known method for easily and inexpensively producing iron-nickel alloy powder having such excellent properties. For example, Patent Document 3 discloses a method for producing nickel-iron alloy nanoparticles by a wet method. In this method, a nucleating agent consisting of a water-soluble salt of a metal nobler than nickel or a hydroxycarboxylic acid is disclosed. No complexing agent consisting of such substances is used. Therefore, it is presumed that the alloy powder produced by this method is inferior in its powder characteristics (particle size, particle size distribution, spheroidity, surface texture of particles). In fact, Patent Document 3 shows a transmission electron micrograph of a fine powder as an example sample (FIG. 1 of Patent Document 3), and as estimated from this photograph, the coefficient of variation (CV value) in the particle size distribution of the fine powder is shown. ) Is as large as about 35%.

Moreover, in the method of Patent Document 3 which does not use a nucleating agent or a complexing agent, it is necessary to use a large amount of reducing agent (hydrazine) in order to obtain a fine alloy powder. In fact, in the examples of Patent Document 3, alloy nanoparticles using 16.6 g of nickel chloride hexahydrate, 4.0 g of ferrous chloride tetrahydrate, and 135 g of hydrazine position hydrate as raw materials. Is being manufactured. When converted from this blending amount, it means that a large amount of hydrazine is blended, which is about 30 times the molar ratio of the total amount of iron and nickel. Such a method requiring a large amount of hydrazine is not practical because the cost of the reducing agent is significantly increased.

The present invention will be described in more detail with reference to the following examples and comparative examples. However, the present invention is not limited to the following examples.

(1) Preparation of Iron-Nickel Alloy Powder [Example 1]
In Example 1, an iron-nickel alloy powder (iron-nickel alloy powder) containing 50 mol% of iron (Fe) and 50 mol% of nickel (Ni) was prepared according to the procedure shown in FIG. In Example 1, when preparing the reaction solution, a reduction solution at room temperature was added to the metal salt raw material solution heated using a water bath and mixed.

<Preparation process>
Ferrous chloride tetrahydrate (FeCl 2.4H ₂ O, molecular weight: 198.81, reagent manufactured by Wako Pure Chemical Industries, Ltd.) was used as a water-soluble iron salt, and nickel chloride hexahydrate (FeCl 2.4H ₂ O, reagent manufactured by Wako Pure Chemical Industries, Ltd.) was used as a water-soluble nickel salt. NiCl _{2.6H 2} _O , molecular weight: 237.69, reagent manufactured by Wako Pure Chemical Industries, Ltd.) were prepared respectively. Also, as a nucleating agent, palladium (II) chloride ammonium (also known as: ammonium tetrachloropalladium (II) acid) ((NH ₄ ) ₂ PdCl ₄ , molecular weight: 284.31, reagent manufactured by Wako Pure Chemical Industries, Ltd.) is complicated. As an agent, trisodium citrate dihydrate (Na ₃ (C _3H ₅ O (COO) ₃ ), 2H ₂ O, molecular weight: 294.1, reagent manufactured by Wako Pure Chemical Industries, Ltd.) is commercially available as a reducing agent. An industrial grade 60% by mass hydrazine hydrate (manufactured by MGC Otsuka Chemical Industries, Ltd.) was prepared, and sodium hydroxide (NaOH, molecular weight: 40.0, reagent manufactured by Wako Pure Chemical Industries, Ltd.) was prepared as a pH adjuster. The 60% by mass hydrazine hydrate was obtained by diluting hydrazine hydrate ₍ _N2 H4 · _H2O , molecular weight: 50.06) 1.67 times with pure water. Further, ethylenediamine (EDA; H ₂ NC ₂ H ₄ NH ₂ , molecular weight: 60.1, reagent manufactured by Wako Pure Chemical Industries, Ltd.) was prepared as an amine compound.

<Crystalization process>
(A) Preparation of metal salt raw material solution Ferrous chloride tetrahydrate (water-soluble iron salt), nickel chloride hexahydrate (water-soluble nickel salt), palladium (II) chloride ammonium (nuclear agent), citric acid A metal salt raw material solution containing trisodium dihydrate (complexing agent) and water was prepared. At this time, in the obtained metal salt raw material solution, weighing was performed so that the amount of palladium (Pd) with respect to the total amount of magnetic metals (Fe and Ni) was 0.037 mass ppm (0.02 mol ppm). Further, weighing was performed so that the amount of trisodium citrate with respect to the total amount of magnetic metals (Fe and Ni) was 0.362 (36.2 mol%) in terms of molar ratio. Specifically, ferrous chloride tetrahydrate: 173.60 g, nickel chloride hexahydrate: 207.55 g, palladium (II) chloride ammonium: 9.93 μg, and trisodium citrate dihydrate: 185.9 g was dissolved in pure water: 1200 mL to prepare a metal salt raw material solution.

(B) Preparation of reducing agent solution A reducing agent solution containing sodium hydroxide (pH adjuster), hydrazine (reducing agent) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, weighing was performed so that the amount of hydrazine with respect to the total amount of magnetic metals (Fe and Ni) was 4.85 in terms of molar ratio. Further, weighing was performed so that the amount of sodium hydroxide with respect to the total amount of magnetic metals (Fe and Ni) was 4.96 in terms of molar ratio. Specifically, sodium hydroxide: 346 g is dissolved in pure water: 850 mL to prepare a sodium hydroxide solution, and 60% by mass of hydrazine hydrate: 707 g is added to and mixed with this sodium hydroxide solution to prepare a reducing agent solution. Was prepared.

(C) Preparation of amine compound solution An amine compound solution containing ethylenediamine (amine compound) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, weighing is performed so that the amount of ethylenediamine with respect to the total amount of magnetic metals (Fe and Ni) is as small as 0.01 (1.0 mol%) in terms of molar ratio. rice field. Specifically, 1.05 g of ethylenediamine was dissolved in 18 mL of pure water to prepare an amine compound solution.

(D) Preparation of reaction solution and precipitation of crystallization powder The prepared metal salt raw material solution was placed in a Teflon (registered trademark) -coated stainless steel container (reaction tank) with a stirring blade installed in a water bath, and the liquid temperature was 70. The mixture was heated while stirring to reach ° C. Then, a reducing agent solution having a liquid temperature of 25 ° C. was added to and mixed with the metal salt raw material solution heated in the water bath for a mixing time of 10 seconds to obtain a reaction liquid having a liquid temperature of 55 ° C. The concentration of magnetic metals (Fe and Ni) in the reaction solution was 32.3 g / L. As a result, the reduction reaction (crystallization reaction) was started (reaction start temperature 55 ° C.). As shown in FIG. 7, the temperature of the reaction solution continued to rise by heating with a water bath after the start of the reaction, and was maintained at the liquid temperature of 70 ° C. after 10 minutes from the start of the reaction (reaction holding temperature 70 ° C.). The color tone of the reaction solution was dark green immediately after the start of the reaction (preparation of the reaction solution), but changed to dark gray after a few minutes. The color tone immediately after the start of the reaction turned dark green because the reaction according to the above formula (6) proceeded and both iron hydroxide (Fe (OH) ₂ ) and nickel hydroxide (Ni (OH) ₂ ) were used. It is considered that the deposit was formed in the reaction solution. The color tone changed to dark gray several minutes after the start of the reaction, probably because nucleation occurred due to the action of the nucleating agent (palladium salt).

The amine compound solution was added dropwise to the reaction solution over 10 minutes from 3 minutes to 13 minutes after the start of the reaction when the color tone of the reaction solution changed to dark gray, and the reduction reaction proceeded. As a result, iron-nickel crystallization powder was deposited in the reaction solution. The color tone of the reaction solution at this time was black, but the supernatant solution of the reaction solution became transparent within 20 minutes from the start of the reaction. It is considered that the reduction reaction of the above formula (6) was completed and all of the iron component and the nickel component in the reaction solution were reduced to metallic iron and metallic nickel. The reaction solution after the reaction was completed was a slurry containing iron-nickel crystallization powder.

<Recovery process>
The slurry-like reaction liquid obtained in the crystallization step was subjected to filtration washing and solid-liquid separation treatment to recover cake-like iron-nickel crystallization powder. Filtration washing was performed using pure water having a conductivity of 1 μS / cm until the conductivity of the filtrate filtered from the slurry became 10 μS / cm or less. The recovered cake-like crystallization powder was dried in a vacuum dryer set at 50 ° C. Then, the dried crystallization powder was cooled to 35 ° C. in a vacuum, and then nitrogen gas containing 1.0% by volume of oxygen was supplied to slowly oxidize the crystallization powder. In this way, an iron-nickel alloy powder was obtained. The obtained alloy powder was composed of spherical particles having a smooth surface. The particle size distribution was sharp and the average particle size was 0.41 μm.

[Example 2]
In Example 2, an iron-nickel alloy powder (iron-nickel-cobalt) containing 50 mol% of iron (Fe), 40 mol% of nickel (Ni) and 10 mol% of cobalt (Co) was according to the procedure shown in FIG. Cobalt powder) was produced. In Example 2, when preparing the reaction solution, a pH adjustment solution (alkali hydroxide solution) at room temperature is first added to the metal salt raw material solution heated using a water bath, and then a reducing agent solution at room temperature is added. And mixed.

<Preparation process>
The same raw materials as in Example 1 were prepared as a water-soluble iron salt, a water-soluble nickel salt, a nucleating agent, a complexing agent, a reducing agent, a pH adjuster, and an amine compound. In addition, cobalt chloride hexahydrate (CoCl _{2.6H 2} _O , molecular weight: 237.93 Wako Pure Chemical Industries, Ltd. reagent) was prepared as a water-soluble cobalt salt.

<Crystalization process>
(A) Preparation of metal salt raw material solution Ferrous chloride tetrahydrate (water-soluble iron salt), nickel chloride hexahydrate (water-soluble nickel salt), cobalt chloride hexahydrate (water-soluble cobalt salt), A metal salt raw material solution containing palladium (II) chloride ammonium (nucleating agent), trisodium citrate dihydrate (complexing agent) and water was prepared. At this time, in the obtained metal salt raw material solution, the amount of palladium (Pd) is 0.037 mass ppm (0.02 mol ppm) with respect to the total amount of magnetic metals (Fe, Ni and Co). gone. Further, weighing was performed so that the amount of trisodium citrate with respect to the total amount of magnetic metals (Fe, Ni and Co) was 0.362 (36.2 mol%) in terms of molar ratio. Specifically, ferrous chloride tetrahydrate: 173.60 g, nickel chloride hexahydrate: 166.04 g, cobalt chloride hexahydrate: 41.55 g, palladium (II) chloride ammonium: 9.93 μg. , And disodium trisodium dihydrate: 185.9 g was dissolved in pure water: 1200 mL to prepare a metal salt raw material solution.

(B) Preparation of reducing agent solution A reducing agent solution containing hydrazine (reducing agent) and water was prepared. At this time, the amount of hydrazine compounded was set so that the molar ratio to the total amount of magnetic metals (Fe, Ni and Co) was 4.85 in the reaction solution prepared in the subsequent crystallization step. Specifically, a reducing agent solution was prepared by weighing 60% by mass of hydrazine hydrate: 707 g.

(C) Preparation of pH adjusting solution (alkali hydroxide solution) A pH adjusting solution (alkali hydroxide solution) containing sodium hydroxide (pH regulator) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, weighing was performed so that the amount of sodium hydroxide with respect to the total amount of magnetic metals (Fe, Ni and Co) was 4.96 in terms of molar ratio. Specifically, 346 g of sodium hydroxide was dissolved in 850 mL of pure water to prepare a pH adjustment solution.

(D) Preparation of amine compound solution An amine compound solution containing ethylenediamine (amine compound) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, the amount of ethylenediamine blended with respect to the total amount of magnetic metals (Fe, Ni and Co) is as small as 0.01 (1.0 mol%) in terms of molar ratio. Weighing was done. Specifically, 1.05 g of ethylenediamine was dissolved in 18 mL of pure water to prepare an amine compound solution.

(E) Preparation of reaction solution and precipitation of crystallization powder The prepared metal salt raw material solution is placed in a Teflon (registered trademark) -coated stainless steel container (reaction tank) with a stirring blade installed in a water bath, and the liquid temperature is 70. The mixture was heated while stirring to reach ° C. After that, a pH adjustment solution (alkali hydroxide solution) having a liquid temperature of 25 ° C. was added and mixed with the metal salt raw material solution heated in the water bath for a mixing time of 10 seconds, and then a reducing agent solution having a liquid temperature of 25 ° C. was added and mixed. Was added and mixed for a mixing time of 10 seconds to obtain a reaction solution having a solution temperature of 55 ° C. The concentration of the magnetic metal (Fe, Ni and Co) in the reaction solution was 32.3 g / L. As a result, the reduction reaction (crystallization reaction) was started (reaction start temperature 55 ° C.). The temperature of the reaction solution continued to rise by heating with a water bath after the start of the reaction, and was maintained at the liquid temperature of 70 ° C. after 10 minutes from the start of the reaction (reaction holding temperature 70 ° C.). The color tone of the reaction solution was dark green immediately after the start of the reaction (preparation of the reaction solution), but changed to dark gray after a few minutes. The color tone immediately after the start of the reaction turned dark green because the reaction proceeded according to the above formula (6), and iron hydroxide (Fe (OH) ₂ ), nickel hydroxide (Ni (OH) ₂ ), and water. It is considered that a co-precipitate of cobalt oxide (Co (OH) ₂ ) was formed in the reaction solution. The color tone changed to dark gray several minutes after the start of the reaction, probably because nucleation occurred due to the action of the nucleating agent (palladium salt).

The amine compound solution was added dropwise to the reaction solution over 10 minutes from 3 minutes to 13 minutes after the start of the reaction when the color tone of the reaction solution changed to dark gray, and the reduction reaction proceeded. As a result, iron-nickel-cobalt crystallization powder was deposited in the reaction solution. The color tone of the reaction solution at this time was black, but the supernatant solution of the reaction solution became transparent within 20 minutes from the start of the reaction. It is considered that the reduction reaction of the above formula (6) was completed and all of the iron component, nickel component and cobalt component in the reaction solution were reduced to metallic iron, metallic nickel and metallic cobalt. The reaction solution after the reaction was completed was a slurry containing iron-nickel-cobalt crystallization powder.

<Recovery process>
The slurry-like reaction liquid obtained in the crystallization step was subjected to filtration washing and solid-liquid separation treatment to recover cake-like iron-nickel-cobalt crystallization powder. Filtration washing was performed using pure water having a conductivity of 1 μS / cm until the conductivity of the filtrate filtered from the slurry became 10 μS / cm or less. The recovered cake-like crystallization powder was dried in a vacuum dryer set at 50 ° C. Then, the dried crystallization powder was cooled to 35 ° C. in a vacuum, and then nitrogen gas containing 1.0% by volume of oxygen was supplied to slowly oxidize the crystallization powder. In this way, an iron-nickel-cobalt alloy powder was obtained. The obtained alloy powder was composed of spherical particles having a smooth surface. The particle size distribution was sharp and the average particle size was 0.33 μm.

[Example 3]
In Example 3, an iron-nickel alloy powder (iron-nickel alloy powder) containing 50 mol% of iron (Fe) and 50 mol% of nickel (Ni) was prepared according to the procedure shown in FIG. In Example 3, when preparing the reaction solution, a reduction solution at room temperature was added to the metal salt raw material solution heated using a water bath and mixed.

<Preparation process>
The same raw materials as in Example 1 were prepared as a water-soluble iron salt, a water-soluble nickel salt, a nucleating agent, a reducing agent, a pH adjuster, and an amine compound. As a complexing agent, tartaric acid ((CH (OH) COOH) ₂ , molecular weight: 150.09, reagent manufactured by Wako Pure Chemical Industries, Ltd.) was prepared instead of trisodium citrate dihydrate.

<Crystalization process>
(A) Preparation of metal salt raw material solution Ferrous chloride tetrahydrate (water-soluble iron salt), nickel chloride hexahydrate (water-soluble nickel salt), palladium (II) chloride ammonium (nuclear agent), tartrate (tartrate) A metal salt raw material solution containing a complexing agent) and water was prepared. At this time, in the obtained metal salt raw material solution, weighing was performed so that the amount of palladium (Pd) was 0.037 mass ppm (0.02 mol ppm) with respect to the total amount of magnetic metals (Fe and Ni). .. Further, weighing was performed so that the amount of tartaric acid with respect to the total amount of magnetic metals (Fe and Ni) was 0.200 (20.0 mol%) in terms of molar ratio. Specifically, ferrous chloride tetrahydrate: 173.60 g, nickel chloride hexahydrate: 207.55 g, palladium (II) chloride ammonium: 9.93 μg, and tartrate acid: 52.4 g as pure water: A metal salt raw material solution was prepared by dissolving in 1200 mL.

(C) Preparation of amine compound solution An amine compound solution was prepared in the same manner as in Example 1.

(D) Preparation of reaction solution and precipitation of crystallization powder Using the above metal salt raw material solution, reducing agent solution, and amine compound solution, the reaction solution was prepared and the crystallization powder was precipitated in the same manner as in Example 1. rice field. The concentration of magnetic metals (Fe and Ni) in the reaction solution was 33.0 g / L.

<Recovery process>
An iron-nickel alloy powder (iron-nickel alloy powder) was produced from the slurry-like reaction solution obtained in the crystallization step in the same manner as in Example 1. The obtained alloy powder was composed of spherical particles having a smooth surface. The particle size distribution was sharp and the average particle size was 0.40 μm.

[Example 4]
In Example 4, an iron-nickel alloy powder (iron-nickel alloy powder) containing 56 mol% of iron (Fe) and 44 mol% of nickel (Ni) was prepared according to the procedure shown in FIG. In Example 4, when preparing the reaction solution, a metal salt raw material solution at room temperature was added to the reducing solution heated using a water bath and mixed.

<Preparation process>
The same raw materials as in Example 1 were prepared as a nucleating agent, a reducing agent, a pH adjusting agent, a complexing agent, and an amine compound. In addition, as a water-soluble iron salt, instead of ferrous chloride tetrahydrate, ferrous sulfate heptahydrate (FeSO _4.7H ₂ O, molecular weight: 278.05, reagent manufactured by Wako Pure Chemical Industries, Ltd.) ) As a water-soluble nickel salt, instead of nickel chloride hexahydrate, prepare nickel sulfate hexahydrate (NiSO _4.6H ₂ O, molecular weight: 262.85, reagent manufactured by Wako Pure Chemical Industries, Ltd.). bottom.

<Crystalization process>
(A) Preparation of metal salt raw material solution Ferrous sulfate heptahydrate (water-soluble iron salt), nickel sulfate hexahydrate (water-soluble nickel salt), palladium (II) chloride ammonium (nuclear agent), citric acid A metal salt raw material solution containing trisodium dihydrate (complexing agent) and water was prepared. At this time, in the obtained metal salt raw material solution, weighing was performed so that the amount of palladium (Pd) was 0.37 mass ppm (0.2 mol ppm) with respect to the total amount of magnetic metals (Fe and Ni). .. Further, weighing was performed so that the amount of trisodium citrate dihydrate with respect to the total amount of magnetic metals (Fe and Ni) was 0.318 (31.8 mol%) in terms of molar ratio. Specifically, ferrous sulfate heptahydrate: 272.0 g, nickel sulfate hexahydrate: 202.0 g, palladium (II) chloride ammonium: 99.3 μg, and trisodium citrate dihydrate: 163.5 g was dissolved in pure water: 950 mL to prepare a metal salt raw material solution.

(B) Preparation of reducing agent solution A reducing agent solution containing sodium hydroxide (pH adjuster), hydrazine (reducing agent) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, weighing was performed so that the amount of hydrazine with respect to the total amount of magnetic metals (Fe and Ni) was 6.41 in terms of molar ratio. Further, weighing was performed so that the amount of sodium hydroxide with respect to the total amount of magnetic metals (Fe and Ni) was 4.67 in terms of molar ratio. Specifically, sodium hydroxide: 326 g is dissolved in pure water: 800 mL to prepare a sodium hydroxide solution, and 60% by mass of hydrazine hydrate: 934 g is added to and mixed with this sodium hydroxide solution to prepare a reducing agent solution. Was prepared.

(D) Preparation of reaction solution and precipitation of crystallization powder The prepared reducing agent solution was placed in a Teflon (registered trademark) -coated stainless steel container (reaction tank) with a stirring blade installed in a water bath, and the solution temperature was 70 ° C. It was heated while stirring so as to become. Then, a metal salt raw material solution having a liquid temperature of 25 ° C. was added to and mixed with the reducing agent solution heated in a water bath for a mixing time of 10 seconds to obtain a reaction liquid having a liquid temperature of 59 ° C. The concentration of magnetic metals (Fe and Ni) in the reaction solution was 32.6 g / L. As a result, the reduction reaction (crystallization reaction) was started (reaction start temperature 59 ° C.). The temperature of the reaction solution continued to rise by heating with a water bath after the start of the reaction, and was maintained at the liquid temperature of 70 ° C. after 10 minutes from the start of the reaction (reaction holding temperature 70 ° C.). The color tone of the reaction solution was dark green immediately after the start of the reaction (preparation of the reaction solution), but changed to dark gray after a few minutes. The color tone immediately after the start of the reaction turned dark green because the reaction according to the above formula (6) proceeded and both iron hydroxide (Fe (OH) ₂ ) and nickel hydroxide (Ni (OH) ₂ ) were used. It is considered that the deposit was formed in the reaction solution. The color tone changed to dark gray several minutes after the start of the reaction, probably because nucleation occurred due to the action of the nucleating agent (palladium salt).

The amine compound solution was added dropwise to the reaction solution over 10 minutes from 3 minutes to 13 minutes after the start of the reaction when the color tone of the reaction solution changed to dark gray, and the reduction reaction proceeded. As a result, iron-nickel crystallization powder was deposited in the reaction solution. The color tone of the reaction solution at this time was black, but the supernatant solution of the reaction solution became transparent within 30 minutes from the start of the reaction. It is considered that the reduction reaction of the above formula (6) was completed and all of the iron component and the nickel component in the reaction solution were reduced to metallic iron and metallic nickel. The reaction solution after the reaction was completed was a slurry containing iron-nickel crystallization powder.

<Recovery process>
The slurry-like reaction liquid obtained in the crystallization step was subjected to filtration washing and solid-liquid separation treatment to recover cake-like iron-nickel crystallization powder. Filtration washing was performed using pure water having a conductivity of 1 μS / cm until the conductivity of the filtrate filtered from the slurry became 10 μS / cm or less. The recovered cake-like crystallization powder was dried in a vacuum dryer set at 50 ° C. Then, the dried crystallization powder was cooled to 35 ° C. in a vacuum, and then nitrogen gas containing 1.0% by volume of oxygen was supplied to slowly oxidize the crystallization powder. In this way, an iron-nickel alloy powder was obtained. The obtained alloy powder was composed of spherical particles having a smooth surface. The particle size distribution was sharp and the average particle size was 0.38 μm.

[Example 5]
In Example 5, an iron-nickel alloy powder (iron-nickel alloy powder) containing 51 mol% of iron (Fe) and 49 mol% of nickel (Ni) having a nickel-rich surface composition according to the procedure shown in FIG. Was produced. At this time, an additional raw material liquid was added and mixed at the end of the crystallization step. Specifically, iron-nickel alloy powder (iron) containing 56 mol% of iron (Fe) and 44 mol% of nickel (Ni) in the same manner as in Example 4 except that the amount of hydrazine as a reducing agent is different. -The crystallization of nickel alloy powder) was advanced, and in the middle of this crystallization, a water-soluble nickel salt aqueous solution as an additional raw material solution was added and mixed with the reaction solution.

<Preparation process>
The same raw materials as in Example 4 were prepared as a water-soluble iron salt, a water-soluble nickel salt, a nucleating agent, a reducing agent, a pH adjuster, a complexing agent, and an amine compound.

<Crystalization process>
(A) Preparation of metal salt raw material solution Ferrous sulfate heptahydrate (water-soluble iron salt), nickel sulfate hexahydrate (water-soluble nickel salt), palladium (II) chloride ammonium (nuclear agent), citric acid A metal salt raw material solution containing trisodium dihydrate (complexing agent) and water was prepared. At this time, in the obtained metal salt raw material solution, weighing was performed so that the amount of palladium (Pd) was 0.37 mass ppm (0.2 mol ppm) with respect to the total amount of magnetic metals (Fe and Ni). .. Further, weighing was performed so that the molar ratio of trisodium citrate dihydrate to the total amount of magnetic metals (Fe and Ni) was 0.318 (31.8 mol%). Specifically, ferrous sulfate heptahydrate: 272.0 g, nickel sulfate hexahydrate: 202.0 g, palladium (II) chloride ammonium: 99.3 μg, and trisodium citrate dihydrate: 163.5 g was dissolved in pure water: 950 mL to prepare a metal salt raw material solution.

(B) Preparation of reducing agent solution A reducing agent solution containing sodium hydroxide (pH adjuster), hydrazine (reducing agent) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, the amount of hydrazine with respect to the total amount of magnetic metals (Fe and Ni) at the start of the reaction was 4.85 in terms of molar ratio (magnetic metals (Fe and Ni) at the time of adding the additional raw material solution). Ni) Weighing was performed so that the molar ratio of the total amount was 4.41). The amount of sodium hydroxide with respect to the total amount of magnetic metals (Fe and Ni) at the start of the reaction was 4.67 in terms of molar ratio (4 in terms of molar ratio with respect to the total amount of magnetic metals (Fe and Ni) at the time of adding the additional raw material liquid). Weighing was performed so as to be .24). Specifically, sodium hydroxide: 326 g is dissolved in pure water: 800 mL to prepare a sodium hydroxide solution, and 60% by mass of hydrazine hydrate: 707 g is added to and mixed with this sodium hydroxide solution to prepare a reducing agent solution. Was prepared.

(C) Preparation of amine compound solution An amine compound solution containing ethylenediamine (amine compound) and water was prepared. At this time, in the reaction solution in the subsequent crystallization step, the amount of ethylenediamine with respect to the total amount of magnetic metals (Fe and Ni) after the addition of the additional raw material solution is as small as 0.01 (1.0 mol%) in terms of molar ratio. Weighed in. Specifically, 1.16 g of ethylenediamine was dissolved in 18 mL of pure water to prepare an amine compound solution.

(D) Preparation of additional raw material liquid An additional raw material liquid containing nickel sulfate hexahydrate (water-soluble nickel salt) and water was prepared. At this time, the amount of magnetic metal (Ni) in the obtained additional raw material solution was 0.175 mol, which was 0.10 with respect to 1.747 mol of the total amount of magnetic metal (Fe and Ni) in the metal salt raw material solution. Weighing was performed so as to be doubled. Specifically, nickel sulfate hexahydrate: 46.0 g was dissolved in pure water: 200 mL to prepare an additional raw material solution.

(E) Preparation of reaction solution and precipitation of crystallization powder The prepared reducing agent solution was placed in a Teflon (registered trademark) -coated stainless steel container (reaction tank) with a stirring blade installed in a water bath, and the liquid temperature was 70 ° C. It was heated while stirring so as to become. Then, a metal salt raw material solution having a liquid temperature of 25 ° C. was added to and mixed with the reducing agent solution heated in a water bath for a mixing time of 10 seconds to obtain a reaction liquid having a liquid temperature of 57 ° C. The concentration of magnetic metals (Fe and Ni) in the reaction solution was 35.2 g / L. As a result, the reduction reaction (crystallization reaction) was started (reaction start temperature 57 ° C.). The temperature of the reaction solution continued to rise by heating with a water bath after the start of the reaction, and was maintained at the liquid temperature of 70 ° C. after 10 minutes from the start of the reaction (reaction holding temperature 70 ° C.). The color tone of the reaction solution was dark green immediately after the start of the reaction (preparation of the reaction solution), but changed to dark gray after a few minutes. The color tone immediately after the start of the reaction turned dark green because the reaction according to the above formula (6) proceeded and both iron hydroxide (Fe (OH) ₂ ) and nickel hydroxide (Ni (OH) ₂ ) were used. It is considered that the deposit was formed in the reaction solution. The color tone changed to dark gray several minutes after the start of the reaction, probably because nucleation occurred due to the action of the nucleating agent (palladium salt).

The amine compound solution was added dropwise to the reaction solution over 10 minutes from 3 minutes to 13 minutes after the start of the reaction when the color tone of the reaction solution changed to dark gray, and the reduction reaction proceeded. As a result, iron-nickel crystallization powder was deposited in the reaction solution. Precipitated iron-nickel crystallized powder while promoting the reduction of iron ions (or iron hydroxide) that are difficult to reduce by adding and mixing the additional raw material liquid little by little from 11 minutes to 16 minutes after the start of the reaction. The reduction reaction was carried out so that the surface of the iron had a more nickel-rich composition. The concentration of the magnetic metal (Fe and Ni) in the reaction solution after the addition of the additional raw material solution was 32.8 g / L. The color tone of the reaction solution at this time was black, but the supernatant solution of the reaction solution became transparent within 30 minutes from the start of the reaction. It is considered that all the reduction reactions were completed and all the iron components and nickel components in the reaction solution were reduced to metallic iron and metallic nickel. The reaction solution after the reaction was completed was a slurry containing iron-nickel crystallization powder.

<Recovery process>
The slurry-like reaction liquid obtained in the crystallization step was subjected to filtration washing and solid-liquid separation treatment to recover cake-like iron-nickel crystallization powder. Filtration washing was performed using pure water having a conductivity of 1 μS / cm until the conductivity of the filtrate filtered from the slurry became 10 μS / cm or less. The recovered cake-like crystallization powder was dried in a vacuum dryer set at 50 ° C. Then, the dried crystallization powder was cooled to 35 ° C. in a vacuum, and then nitrogen gas containing 1.0% by volume of oxygen was supplied to slowly oxidize the crystallization powder. In this way, an iron-nickel alloy powder was obtained. The obtained alloy powder was composed of spherical particles having a smooth surface. The particle size distribution was sharp and the average particle size was 0.40 μm.

[Example 6]
In Example 6, the crystallization powder obtained in Example 1 was dry-crushed using an ultra-small jet crusher (Nippon Pneumatic Co., Ltd., JKE-30) at a crushing gas pressure of 0.5 MPa. The spiral jet crushing treatment was carried out to prepare an iron-nickel alloy powder (iron-nickel alloy powder) containing 50 mol% of iron (Fe) and 50 mol% of nickel (Ni). The obtained alloy powder had a sharp particle size distribution as in Example 1, and the average particle size was 0.41 μm. In addition, the spiral jet crushing treatment reduced the agglomerated particles and improved the filling property (increased powder density), and also reduced the surface irregularities and composed of very smooth spherical particles.

[Example 7]
In Example 7, following the crystallization step, iron (Fe) 50 is subjected to high-pressure fluid collision crushing treatment, which is wet crushing, on the slurry-like crystallization powder before drying in the middle of the recovery step. An iron-nickel alloy powder (iron-nickel alloy powder) containing mol% and 50 mol% of nickel (Ni) was prepared.

<Recovery process (including crushing process)>
A slurry-like reaction solution containing iron-nickel crystallization powder obtained in the same crystallization step as in Example 1 was filtered and washed, and then iron-nickel crystallization was performed using pure water having a conductivity of 1 μS / cm. A washed crystallization powder slurry having a powder concentration of 20% by mass was prepared. The above-mentioned filtration washing was carried out using pure water having a conductivity of 1 μS / cm until the conductivity of the filtrate filtered from the slurry became 10 μS / cm or less. The above-mentioned washed crystallization powder slurry was passed through a high-pressure fluid collision crusher (manufactured by Sugino Machine; pressure: 200 MPa) for 2 passes to perform crushing treatment, and then solid-liquid separation treatment was performed to form a cake-like iron. Nickel crystallization powder was recovered. The recovered cake-like crystallization powder was dried in a vacuum dryer set at 50 ° C. Then, after cooling the dried crystallization powder to 35 ° C. in vacuum, nitrogen gas containing 1.0% by volume of oxygen is supplied, and the crystallization powder is subjected to a slow oxidation treatment to obtain an iron-nickel alloy powder. rice field. The obtained alloy powder had a sharp particle size distribution as in Example 1, and the average particle size was 0.41 μm. In addition, the high-pressure fluid collision crushing treatment reduced the agglomerated particles and improved the filling property (increased powder density), and also reduced the surface irregularities and composed of very smooth spherical particles.

[Example 8]
In Example 8, the crystallization powder obtained according to the procedure shown in FIG. 6 is subjected to high-temperature heat treatment to obtain an iron-nickel alloy powder (iron) containing 65 mol% of iron (Fe) and 35 mol% of nickel (Ni). -Nickel alloy powder) was prepared. In Example 8, when preparing the reaction solution, a metal salt raw material solution at room temperature was added to the reducing solution heated using a water bath and mixed.

<Crystalization process>
(A) Preparation of metal salt raw material solution Ferrous sulfate heptahydrate (water-soluble iron salt), nickel sulfate hexahydrate (water-soluble nickel salt), palladium (II) chloride ammonium (nuclear agent), citric acid A metal salt raw material solution containing trisodium dihydrate (complexing agent) and water was prepared. At this time, in the obtained metal salt raw material solution, weighing was performed so that the amount of palladium (Pd) was 2.81 parts by mass (1.50 mol ppm) with respect to the total amount of magnetic metals (Fe and Ni). .. Further, weighing was performed so that the molar ratio of trisodium citrate dihydrate to the total amount of magnetic metals (Fe and Ni) was 0.724 (72.4 mol%). Specifically, ferrous sulfate heptahydrate: 318.1 g, nickel sulfate hexahydrate: 161.9 g, palladium (II) chloride ammonium: 750.5 μg, and trisodium citrate dihydrate: 374.7 g was dissolved in pure water: 950 mL to prepare a metal salt raw material solution.

(B) Preparation of reducing agent solution A reducing agent solution containing sodium hydroxide (pH adjuster), hydrazine (reducing agent) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, weighing was performed so that the amount of hydrazine with respect to the total amount of magnetic metals (Fe and Ni) at the start of the reaction was 8.98 in terms of molar ratio. Further, weighing was performed so that the amount of sodium hydroxide with respect to the total amount of magnetic metals (Fe and Ni) at the start of the reaction was 7.07 in terms of molar ratio. Specifically, sodium hydroxide: 497.5 g is dissolved in pure water: 1218 mL to prepare a sodium hydroxide solution, and 60% by mass of hydrazine hydrate: 1318 g is added to and mixed with this sodium hydroxide solution for reduction. A solution of the agent was prepared.

(C) Preparation of amine compound solution An amine compound solution containing ethylenediamine (amine compound) and water was prepared. At this time, in the reaction solution in the subsequent crystallization step, the amount of ethylenediamine with respect to the total amount of magnetic metals (Fe and Ni) after the addition of the additional raw material solution is as small as 0.01 (1.0 mol%) in terms of molar ratio. Weighed in. Specifically, 1.06 g of ethylenediamine was dissolved in 18 mL of pure water to prepare an amine compound solution.

(D) Preparation of reaction solution and precipitation of crystallization powder The prepared reducing agent solution was placed in a Teflon (registered trademark) -coated stainless steel container (reaction tank) with a stirring blade installed in a water bath, and the solution temperature was 80 ° C. It was heated while stirring so as to become. Then, a metal salt raw material solution having a liquid temperature of 25 ° C. was added to and mixed with the reducing agent solution heated in a water bath for a mixing time of 10 seconds to obtain a reaction liquid having a liquid temperature of 71 ° C. The concentration of magnetic metals (Fe and Ni) in the reaction solution was 25.0 g / L. As a result, the reduction reaction (crystallization reaction) was started (reaction start temperature 71 ° C.). The temperature of the reaction solution continued to rise by heating with a water bath after the start of the reaction, and was maintained at the liquid temperature of 80 ° C. after 10 minutes from the start of the reaction (reaction holding temperature 80 ° C.). The color tone of the reaction solution was dark green immediately after the start of the reaction (preparation of the reaction solution), but changed to dark gray after a few minutes. The color tone immediately after the start of the reaction turned dark green because the reaction according to the above formula (6) proceeded and both iron hydroxide (Fe (OH) ₂ ) and nickel hydroxide (Ni (OH) ₂ ) were used. It is considered that the deposit was formed in the reaction solution. The color tone changed to dark gray several minutes after the start of the reaction, probably because nucleation occurred due to the action of the nucleating agent (palladium salt).

The amine compound solution was added dropwise to the reaction solution over 10 minutes from 3 minutes to 13 minutes after the start of the reaction when the color tone of the reaction solution changed to dark gray, and the reduction reaction proceeded. As a result, iron-nickel crystallization powder was deposited in the reaction solution. The color tone of the reaction solution at this time was black, but the supernatant solution of the reaction solution became transparent within 40 minutes from the start of the reaction. It is considered that all the reduction reactions were completed and all the iron components and nickel components in the reaction solution were reduced to metallic iron and metallic nickel. The reaction solution after the reaction was completed was a slurry containing iron-nickel crystallization powder.

<Recovery process>
The slurry-like reaction liquid obtained in the crystallization step was subjected to filtration washing and solid-liquid separation treatment to recover cake-like iron-nickel crystallization powder. Filtration washing was performed using pure water having a conductivity of 1 μS / cm until the conductivity of the filtrate filtered from the slurry became 10 μS / cm or less. The recovered cake-like crystallization powder was dried in a vacuum dryer set at 50 ° C. Then, the dried crystallization powder was cooled to 35 ° C. in a vacuum, and then nitrogen gas containing 1.0% by volume of oxygen was supplied to slowly oxidize the crystallization powder.

<High temperature heat treatment process>
The crystallization powder thus obtained is subjected to high temperature heat treatment by heating at 350 ° C. for 60 minutes in a nitrogen atmosphere, and is an iron-nickel system containing 65 mol% of iron (Fe) and 35 mol% of nickel (Ni). An alloy powder (iron-nickel alloy powder) was prepared. The obtained alloy powder had a sharp particle size distribution as in Example 1, and the average particle size was 0.27 μm. Further, the high temperature heat treatment promoted the diffusion of Fe and Ni in the iron (Fe) -nickel (Ni) alloy particles, improved the composition uniformity in the particles, and reduced the variation in characteristics in the particles.

[Example 9]
In Example 9, an iron-nickel alloy powder (iron-nickel alloy powder) containing 65 mol% of iron (Fe) and 35 mol% of nickel (Ni) having a nickel-rich surface composition according to the procedure shown in FIG. Was produced. At this time, an additional raw material liquid was added and mixed in the middle of the crystallization step. Specifically, a metal salt raw material solution at room temperature is added and mixed with a reduction solution heated using a water bath to prepare a reaction solution. First, iron (Fe) 67.4 mol% and nickel (Ni) 32. Crystallization of iron-nickel alloy powder (iron-nickel alloy powder) containing 6 mol% was advanced. Then, in the middle of this crystallization, a water-soluble nickel salt aqueous solution as an additional raw material solution was added and mixed with the reaction solution.

<Crystalization process>
(A) Preparation of metal salt raw material solution Ferrous sulfate heptahydrate (water-soluble iron salt), nickel sulfate hexahydrate (water-soluble nickel salt), palladium (II) chloride ammonium (nuclear agent), citric acid A metal salt raw material solution containing trisodium dihydrate (complexing agent) and water was prepared. At this time, in the obtained metal salt raw material solution, weighing was performed so that the amount of palladium (Pd) was 0.97 mass ppm (0.52 mol ppm) with respect to the total amount of magnetic metals (Fe and Ni). .. Further, weighing was performed so that the molar ratio of trisodium citrate dihydrate to the total amount of magnetic metals (Fe and Ni) was 0.750 (75.0 mol%). Specifically, ferrous sulfate heptahydrate: 318.1 g, nickel sulfate hexahydrate: 145.7 g, palladium (II) chloride ammonium: 250.0 μg, and trisodium citrate dihydrate: 374.7 g was dissolved in pure water: 500 mL to prepare a metal salt raw material solution.

(B) Preparation of reducing agent solution A reducing agent solution containing sodium hydroxide (pH adjuster), hydrazine (reducing agent) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, the amount of hydrazine with respect to the total amount of magnetic metals (Fe and Ni) at the start of the reaction was 7.62 in terms of molar ratio (magnetic metals (Fe and Ni) at the time of adding the additional raw material solution). Ni) Weighing was performed so that the total amount was 7.36) in terms of molar ratio. The amount of sodium hydroxide with respect to the total amount of magnetic metals (Fe and Ni) at the start of the reaction is 7.33 in terms of molar ratio (7 in terms of molar ratio with respect to the total amount of magnetic metals (Fe and Ni) at the time of adding the additional raw material liquid). Weighing was performed so as to be .07). Specifically, sodium hydroxide: 497.5 g is dissolved in pure water: 1218 mL to prepare a sodium hydroxide solution, and 60% by mass of hydrazine hydrate: 1080 g is added to and mixed with this sodium hydroxide solution for reduction. A solution of the agent was prepared.

(D) Preparation of additional raw material liquid An additional raw material liquid containing nickel sulfate hexahydrate (water-soluble nickel salt) and water was prepared. At this time, the amount of magnetic metal (Ni) in the obtained additional raw material solution was 0.0616 mol, which was 0.035 with respect to 1.760 mol of the total amount of magnetic metal (Fe and Ni) in the metal salt raw material solution. Weighing was performed so as to be doubled. Specifically, an additional raw material solution was prepared by dissolving 16.2 g of nickel sulfate hexahydrate in pure water: 200 mL.

(E) Preparation of reaction solution and precipitation of crystallization powder The prepared reducing agent solution was placed in a Teflon (registered trademark) -coated stainless steel container (reaction tank) with a stirring blade installed in a water bath, and the liquid temperature was 80 ° C. It was heated while stirring so as to become. Then, a metal salt raw material solution having a liquid temperature of 25 ° C. was added to and mixed with the reducing agent solution heated in a water bath for a mixing time of 10 seconds to obtain a reaction liquid having a liquid temperature of 75 ° C. The concentration of magnetic metals (Fe and Ni) in the reaction solution was 29.1 g / L. As a result, the reduction reaction (crystallization reaction) was started (reaction start temperature 75 ° C.). The temperature of the reaction solution continued to rise by heating with a water bath after the start of the reaction, and was maintained at the liquid temperature of 80 ° C. after 10 minutes from the start of the reaction (reaction holding temperature 80 ° C.). The color tone of the reaction solution was dark green immediately after the start of the reaction (preparation of the reaction solution), but changed to dark gray after a few minutes. The color tone immediately after the start of the reaction turned dark green because the reaction according to the above formula (6) proceeded and both iron hydroxide (Fe (OH) ₂ ) and nickel hydroxide (Ni (OH) ₂ ) were used. It is considered that the deposit was formed in the reaction solution. The color tone changed to dark gray several minutes after the start of the reaction, probably because nucleation occurred due to the action of the nucleating agent (palladium salt).

The amine compound solution was added dropwise to the reaction solution over 10 minutes from 3 minutes to 13 minutes after the start of the reaction when the color tone of the reaction solution changed to dark gray, and the reduction reaction proceeded. As a result, iron-nickel crystallization powder was deposited in the reaction solution. From 25 minutes to 35 minutes after the start of the reaction, the additional raw material solution is added and mixed little by little while accelerating the reduction of iron ions (or iron hydroxide) that are difficult to reduce, and the precipitated iron-nickel crystallized powder. The reduction reaction was carried out so that the surface of the iron had a more nickel-rich composition. The concentration of the magnetic metal (Fe and Ni) in the reaction solution after the addition of the additional raw material solution was 28.4 g / L. The color tone of the reaction solution at this time was black, but the supernatant solution of the reaction solution became transparent within 40 minutes from the start of the reaction. It is considered that all the reduction reactions were completed and all the iron components and nickel components in the reaction solution were reduced to metallic iron and metallic nickel. The reaction solution after the reaction was completed was a slurry containing iron-nickel crystallization powder.

<Recovery process>
The slurry-like reaction liquid obtained in the crystallization step was subjected to filtration washing and solid-liquid separation treatment to recover cake-like iron-nickel crystallization powder. Filtration washing was performed using pure water having a conductivity of 1 μS / cm until the conductivity of the filtrate filtered from the slurry became 10 μS / cm or less. The recovered cake-like crystallization powder was dried in a vacuum dryer set at 50 ° C. Then, the dried crystallization powder was cooled to 35 ° C. in a vacuum, and then nitrogen gas containing 1.0% by volume of oxygen was supplied to slowly oxidize the crystallization powder. In this way, an iron-nickel alloy powder was obtained. The obtained alloy powder was composed of spherical particles having a smooth surface. The particle size distribution was sharp and the average particle size was 0.39 μm.

[Example 10]
In Example 10, an iron-nickel alloy powder (iron-nickel alloy powder) containing 80 mol% of iron (Fe) and 20 mol% of nickel (Ni) having a large iron content according to the procedure shown in FIG. Was produced. At this time, an additional raw material liquid was added and mixed in the middle of the crystallization step. Specifically, a metal salt raw material solution at room temperature is added and mixed with a reduction solution heated using a water bath to prepare a reaction solution. First, iron (Fe) 83.3 mol% and nickel (Ni) 16. Crystallization of iron-nickel alloy powder (iron-nickel alloy powder) containing 7 mol% was advanced. Then, in the middle of this crystallization, a water-soluble nickel salt aqueous solution as an additional raw material solution was added and mixed with the reaction solution.

<Crystalization process>
(A) Preparation of metal salt raw material solution Ferrous sulfate heptahydrate (water-soluble iron salt), nickel sulfate hexahydrate (water-soluble nickel salt), palladium (II) chloride ammonium (nuclear agent), citric acid A metal salt raw material solution containing trisodium dihydrate (complexing agent) and water was prepared. At this time, in the obtained metal salt raw material solution, weighing was performed so that the amount of palladium (Pd) was 0.79 mass ppm (0.42 mol ppm) with respect to the total amount of magnetic metals (Fe and Ni). .. Further, weighing was performed so that the molar ratio of trisodium citrate dihydrate to the total amount of magnetic metals (Fe and Ni) was 0.754 (75.4 mol%). Specifically, ferrous sulfate heptahydrate: 394.3 g, nickel sulfate hexahydrate: 74.6 g, palladium (II) chloride ammonium: 201.6 μg, and trisodium citrate dihydrate: 377.5 g was dissolved in pure water: 836 mL to prepare a metal salt raw material solution.

(B) Preparation of reducing agent solution A reducing agent solution containing sodium hydroxide (pH adjuster), hydrazine (reducing agent) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, the amount of hydrazine with respect to the total amount of magnetic metals (Fe and Ni) at the start of the reaction was 9.40 in terms of molar ratio (magnetic metals (Fe and Ni) at the time of adding the additional raw material solution). Ni) Weighing was performed so that the total amount was 9.02) in terms of molar ratio. The amount of sodium hydroxide with respect to the total amount of magnetic metals (Fe and Ni) at the start of the reaction is 7.37 in molar ratio (7 in molar ratio with respect to the total amount of magnetic metals (Fe and Ni) at the time of adding the additional raw material liquid). Weighing was performed so as to be .07). Specifically, 501.3 g of sodium hydroxide is dissolved in 1228 mL of pure water to prepare a sodium hydroxide solution, and 60% by mass of hydrazine hydrate: 1334 g is added to and mixed with this sodium hydroxide solution for reduction. A solution of the agent was prepared.

(C) Preparation of amine compound solution An amine compound solution containing ethylenediamine (amine compound) and water was prepared. At this time, in the reaction solution in the subsequent crystallization step, the amount of ethylenediamine with respect to the total amount of magnetic metals (Fe and Ni) after the addition of the additional raw material solution is as small as 0.01 (1.0 mol%) in terms of molar ratio. Weighed in. Specifically, 1.07 g of ethylenediamine was dissolved in 18 mL of pure water to prepare an amine compound solution.

(D) Preparation of additional raw material liquid An additional raw material liquid containing nickel sulfate hexahydrate (water-soluble nickel salt) and water was prepared. At this time, the amount of magnetic metal (Ni) in the obtained additional raw material solution was 0.0709 mol, which was 0.04 with respect to 1.773 mol of the total amount of magnetic metal (Fe and Ni) in the metal salt raw material solution. Weighing was performed so as to be doubled. Specifically, nickel sulfate hexahydrate: 18.64 g was dissolved in pure water: 200 mL to prepare an additional raw material solution.

(E) Preparation of reaction solution and precipitation of crystallization powder The prepared reducing agent solution was placed in a Teflon (registered trademark) -coated stainless steel container (reaction tank) with a stirring blade installed in a water bath, and the liquid temperature was 80 ° C. It was heated while stirring so as to become. Then, a metal salt raw material solution having a liquid temperature of 25 ° C. was added to and mixed with the reducing agent solution heated in a water bath for a mixing time of 10 seconds to obtain a reaction liquid having a liquid temperature of 71 ° C. The concentration of magnetic metals (Fe and Ni) in the reaction solution was 24.5 g / L. As a result, the reduction reaction (crystallization reaction) was started (reaction start temperature 71 ° C.). The temperature of the reaction solution continued to rise by heating with a water bath after the start of the reaction, and was maintained at the liquid temperature of 80 ° C. after 10 minutes from the start of the reaction (reaction holding temperature 80 ° C.). The color tone of the reaction solution was dark green immediately after the start of the reaction (preparation of the reaction solution), but changed to dark gray after a few minutes. The color tone immediately after the start of the reaction turned dark green because the reaction according to the above formula (6) proceeded and both iron hydroxide (Fe (OH) ₂ ) and nickel hydroxide (Ni (OH) ₂ ) were used. It is considered that the deposit was formed in the reaction solution. The color tone changed to dark gray several minutes after the start of the reaction, probably because nucleation occurred due to the action of the nucleating agent (palladium salt).

The amine compound solution was added dropwise to the reaction solution over 10 minutes from 3 minutes to 13 minutes after the start of the reaction when the color tone of the reaction solution changed to dark gray, and the reduction reaction proceeded. As a result, iron-nickel crystallization powder was deposited in the reaction solution. From 8 minutes to 18 minutes after the start of the reaction, the additional raw material solution is added and mixed little by little while advancing the reduction of iron ions (or iron hydroxide) that are difficult to reduce, and the precipitated iron-nickel crystallized powder. The reduction reaction was carried out so that the surface of the iron had a more nickel-rich composition. The concentration of the magnetic metal (Fe and Ni) in the reaction solution after the addition of the additional raw material solution was 24.2 g / L. The color tone of the reaction solution at this time was black, but the supernatant liquid of the reaction solution became transparent within 60 minutes from the start of the reaction. It is considered that all the reduction reactions were completed and all the iron components and nickel components in the reaction solution were reduced to metallic iron and metallic nickel. The reaction solution after the reaction was completed was a slurry containing iron-nickel crystallization powder.

<Recovery process>
The slurry-like reaction liquid obtained in the crystallization step was subjected to filtration washing and solid-liquid separation treatment to recover cake-like iron-nickel crystallization powder. Filtration washing was performed using pure water having a conductivity of 1 μS / cm until the conductivity of the filtrate filtered from the slurry became 10 μS / cm or less. The recovered cake-like crystallization powder was dried in a vacuum dryer set at 50 ° C. Then, the dried crystallization powder was cooled to 35 ° C. in a vacuum, and then nitrogen gas containing 1.0% by volume of oxygen was supplied to slowly oxidize the crystallization powder. In this way, an iron-nickel alloy powder was obtained. The obtained alloy powder was composed of spherical particles having a smooth surface. The particle size distribution was sharp and the average particle size was 0.48 μm.

[Example 11]
In Example 11, an iron-nickel alloy powder (iron-nickel alloy powder) containing 90 mol% of iron (Fe) and 10 mol% of nickel (Ni) having a large iron content according to the procedure shown in FIG. Was produced. At this time, an additional raw material liquid was added and mixed in the middle of the crystallization step. Specifically, a metal salt raw material solution at room temperature is added and mixed with a reduction solution heated using a water bath to prepare a reaction solution. First, iron (Fe) 91.8 mol% and nickel (Ni) 8. Crystallization of iron-nickel alloy powder (iron-nickel alloy powder) containing 2 mol% was advanced. Then, in the middle of this crystallization, a water-soluble nickel salt aqueous solution as an additional raw material solution was added and mixed with the reaction solution.

<Crystalization process>
(A) Preparation of metal salt raw material solution Ferrous sulfate heptahydrate (water-soluble iron salt), nickel sulfate hexahydrate (water-soluble nickel salt), palladium (II) chloride ammonium (nuclear agent), citric acid A metal salt raw material solution containing trisodium dihydrate (complexing agent) and water was prepared. At this time, in the obtained metal salt raw material solution, weighing was performed so that the amount of palladium (Pd) was 0.77 mass ppm (0.41 mol ppm) with respect to the total amount of magnetic metals (Fe and Ni). .. Further, weighing was performed so that the molar ratio of trisodium citrate dihydrate to the total amount of magnetic metals (Fe and Ni) was 0.369 (36.9 mol%). Specifically, ferrous sulfate heptahydrate: 446.0 g, nickel sulfate hexahydrate: 37.5 g, palladium (II) chloride ammonium: 202.6 μg, and trisodium citrate dihydrate: 189.7 g was dissolved in pure water: 720 mL to prepare a metal salt raw material solution.

(B) Preparation of reducing agent solution A reducing agent solution containing sodium hydroxide (pH adjuster), hydrazine (reducing agent) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, the amount of hydrazine with respect to the total amount of magnetic metals (Fe and Ni) at the start of the reaction was 9.15 in terms of molar ratio (magnetic metals (Fe and Ni) at the time of adding the additional raw material solution). Ni) Weighing was performed so that the total amount was 8.97) in terms of molar ratio. The amount of sodium hydroxide with respect to the total amount of magnetic metals (Fe and Ni) at the start of the reaction was 8.29 in terms of molar ratio (8 in terms of molar ratio with respect to the total amount of magnetic metals (Fe and Ni) at the time of adding the additional raw material liquid). Weighing was performed so as to be .13). Specifically, sodium hydroxide: 579 g is dissolved in pure water: 1418 mL to prepare a sodium hydroxide solution, and 60% by mass of hydrazine hydrate: 1334 g is added to and mixed with this sodium hydroxide solution to prepare a reducing agent solution. Was prepared.

(D) Preparation of additional raw material liquid An additional raw material liquid containing nickel sulfate hexahydrate (water-soluble nickel salt) and water was prepared. At this time, the amount of magnetic metal (Ni) in the obtained additional raw material solution was 0.0356 mol, which was 0.02 with respect to 1.747 mol of the total amount of magnetic metal (Fe and Ni) in the metal salt raw material solution. Weighing was performed so as to be doubled. Specifically, nickel sulfate hexahydrate: 9.37 g was dissolved in pure water: 100 mL to prepare an additional raw material solution.

(E) Preparation of reaction solution and precipitation of crystallization powder The prepared reducing agent solution was placed in a Teflon (registered trademark) -coated stainless steel container (reaction tank) with a stirring blade installed in a water bath, and the liquid temperature was 85 ° C. It was heated while stirring so as to become. Then, a metal salt raw material solution having a liquid temperature of 25 ° C. was added to and mixed with the reducing agent solution heated in a water bath for a mixing time of 10 seconds to obtain a reaction liquid having a liquid temperature of 78 ° C. The concentration of magnetic metals (Fe and Ni) in the reaction solution was 25.0 g / L. As a result, the reduction reaction (crystallization reaction) was started (reaction start temperature 78 ° C.). The temperature of the reaction solution continued to rise by heating with a water bath after the start of the reaction, and was maintained at the liquid temperature of 85 ° C. 10 minutes after the start of the reaction (reaction holding temperature 85 ° C.). The color tone of the reaction solution was dark green immediately after the start of the reaction (preparation of the reaction solution), but changed to dark gray after a few minutes. The color tone immediately after the start of the reaction turned dark green because the reaction according to the above formula (6) proceeded and both iron hydroxide (Fe (OH) ₂ ) and nickel hydroxide (Ni (OH) ₂ ) were used. It is considered that the deposit was formed in the reaction solution. The color tone changed to dark gray several minutes after the start of the reaction, probably because nucleation occurred due to the action of the nucleating agent (palladium salt).

The amine compound solution was added dropwise to the reaction solution over 10 minutes from 3 minutes to 13 minutes after the start of the reaction when the color tone of the reaction solution changed to dark gray, and the reduction reaction proceeded. As a result, iron-nickel crystallization powder was deposited in the reaction solution. From 8 minutes to 18 minutes after the start of the reaction, the additional raw material solution is added and mixed little by little while advancing the reduction of iron ions (or iron hydroxide) that are difficult to reduce, and the precipitated iron-nickel crystallized powder. The reduction reaction was carried out so that the surface of the iron had a more nickel-rich composition. The concentration of the magnetic metal (Fe and Ni) in the reaction solution after the addition of the additional raw material solution was 24.8 g / L. The color tone of the reaction solution at this time was black, but the supernatant solution of the reaction solution became transparent within 50 minutes from the start of the reaction. It is considered that all the reduction reactions were completed and all the iron components and nickel components in the reaction solution were reduced to metallic iron and metallic nickel. The reaction solution after the reaction was completed was a slurry containing iron-nickel crystallization powder.

[Example 12]
In Example 12, the crystallization powder obtained according to the procedure shown in FIG. 5 is subjected to an insulating coating treatment, and iron (Fe) 55 coated with nickel dioxide (SiO ₂ ), which is an insulating metal oxide. An iron-nickel alloy powder (iron-nickel alloy powder) containing mol% and 45 mol% of nickel (Ni) was prepared. In Example 12, when preparing the reaction solution, a metal salt raw material solution at room temperature was added to the reducing solution heated using a water bath and mixed.

<Crystalization process>
(A) Preparation of metal salt raw material solution Ferrous sulfate heptahydrate (water-soluble iron salt), nickel sulfate hexahydrate (water-soluble nickel salt), palladium (II) chloride ammonium (nuclear agent), citric acid A metal salt raw material solution containing trisodium dihydrate (complexing agent) and water was prepared. At this time, in the obtained metal salt raw material solution, weighing was performed so that the amount of palladium (Pd) was 0.56 mass ppm (0.3 mol ppm) with respect to the total amount of magnetic metals (Fe and Ni). .. Further, weighing was performed so that the amount of trisodium citrate dihydrate with respect to the total amount of magnetic metals (Fe and Ni) was 0.543 (54.3 mol%) in terms of molar ratio. Specifically, ferrous sulfate heptahydrate: 267.7 g, nickel sulfate hexahydrate: 207.1 g, palladium (II) chloride ammonium: 149.3 μg, and trisodium citrate dihydrate: 279.6 g was dissolved in pure water: 950 mL to prepare a metal salt raw material solution.

(B) Preparation of reducing agent solution A reducing agent solution containing sodium hydroxide (pH adjuster), hydrazine (reducing agent) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, weighing was performed so that the amount of hydrazine with respect to the total amount of magnetic metals (Fe and Ni) was 4.85 in terms of molar ratio. Further, weighing was performed so that the amount of sodium hydroxide with respect to the total amount of magnetic metals (Fe and Ni) was 4.95 in terms of molar ratio. Specifically, sodium hydroxide: 346 g is dissolved in pure water: 848 mL to prepare a sodium hydroxide solution, and 60% by mass of hydrazine hydrate: 709 g is added to and mixed with this sodium hydroxide solution to prepare a reducing agent solution. Was prepared.

(C) Preparation of amine compound solution An amine compound solution containing ethylenediamine (amine compound) and water was prepared. At this time, in the reaction solution in the subsequent crystallization step, the amount of ethylenediamine with respect to the total amount of magnetic metals (Fe and Ni) after the addition of the additional raw material solution is as small as 0.01 (1.0 mol%) in terms of molar ratio. Weighed in. Specifically, 1.05 g of ethylenediamine was dissolved in 18 mL of pure water to prepare an amine compound solution.

(D) Preparation of reaction solution and precipitation of crystallization powder The prepared reducing agent solution was placed in a Teflon (registered trademark) -coated stainless steel container (reaction tank) with a stirring blade installed in a water bath, and the solution temperature was 70 ° C. It was heated while stirring so as to become. Then, a metal salt raw material solution having a liquid temperature of 25 ° C. was added to and mixed with the reducing agent solution heated in a water bath for a mixing time of 10 seconds to obtain a reaction liquid having a liquid temperature of 59 ° C. The concentration of magnetic metals (Fe and Ni) in the reaction solution was 33.9 g / L. As a result, the reduction reaction (crystallization reaction) was started (reaction start temperature 59 ° C.). The temperature of the reaction solution continued to rise by heating with a water bath after the start of the reaction, and was maintained at the liquid temperature of 70 ° C. after 10 minutes from the start of the reaction (reaction holding temperature 70 ° C.). The color tone of the reaction solution was dark green immediately after the start of the reaction (preparation of the reaction solution), but changed to dark gray after a few minutes. The color tone immediately after the start of the reaction turned dark green because the reaction according to the above formula (6) proceeded and both iron hydroxide (Fe (OH) ₂ ) and nickel hydroxide (Ni (OH) ₂ ) were used. It is considered that the deposit was formed in the reaction solution. The color tone changed to dark gray several minutes after the start of the reaction, probably because nucleation occurred due to the action of the nucleating agent (palladium salt).

<Recovery process>
The slurry-like reaction liquid obtained in the crystallization step was subjected to filtration washing and solid-liquid separation treatment to recover cake-like iron-nickel crystallization powder. Filtration washing was performed using pure water having a conductivity of 1 μS / cm until the conductivity of the filtrate filtered from the slurry became 10 μS / cm or less. The recovered cake-like crystallization powder was dried in a vacuum dryer set at 50 ° C. Then, the dried crystallization powder was cooled to 35 ° C. in a vacuum, and then nitrogen gas containing 1.0% by volume of oxygen was supplied to slowly oxidize the crystallization powder. In this way, a crystallization powder (iron-nickel alloy powder) as a dry powder was obtained. The obtained crystallization powder (alloy powder) was composed of spherical particles having a smooth surface. The particle size distribution was sharp and the average particle size was 0.39 μm.

<Insulation coating process>
50.0 g of the crystallization powder (alkoxide powder) obtained in the above recovery step is placed in a closed polypropylene container, and further, 7.0 g of pure water, ethyl alcohol (C ₂ H ₅ OH, molecular weight: 46.07, sum). After adding 50.0 g of a reagent manufactured by Kojunyaku Kogyo Co., Ltd. and dispersing the above crystallization powder (alloy powder) in a mixed solvent of water and ethyl alcohol, tetraethoxysilane (also known as orthosilicate) as a silicon alkoxide. Tetraethyl acid, tetraethyl silicate) (abbreviation: TEOS) (Si (OC _{2H 5} ₎ ₄ , molecular weight: 208.33, reagent manufactured by Wako Pure Chemical Industries, Ltd.) 9.8 g was added and mixed thoroughly, and further silicon alkoxide was added. 2.4 g of 1% by mass ammonia water as a base catalyst (alkali catalyst) for hydrolysis was added with stirring to obtain a uniform slurry. The 1% by mass ammonia water is a reagent obtained by diluting 28 to 30% by mass ammonia water (NH ₃ , molecular weight: 17.03, reagent manufactured by Wako Pure Chemical Industries, Ltd.) with pure water and crystallization. The powder (alloy powder), water, ethyl alcohol, tetraethoxysilane, and 1% by mass aqueous ammonia are all used at room temperature, and addition and mixing are all performed at room temperature.

The above slurry containing crystallization powder (alloy powder), water, ethyl alcohol, tetraethoxysilane, and ammonia is kept at 40 ° C. for 2 days in a rotating polypropylene airtight container, and the slurry is stirred while tetraethoxy. By advancing the hydrolysis and dehydration shrink polymerization of silane, the surface of the particles of the crystallization powder (alloy powder) contains a hydrolyzed polymer of tetraethoxysilane (silanol group (Si—OH) in a small amount, but almost silicon dioxide (SiO ₂ ). ) Was formed as the main component of the insulating coat layer. After that, the slurry was subjected to filtration washing and solid-liquid separation treatment to recover cake-like crystallization powder (alloy powder). Filtration washing was first performed using ethanol containing 50% by mass of pure water, and then using ethanol. The hydrolyzate polymer of tetraethoxysilane that remains in the slurry without being consumed by the insulating coat on the particle surface of the crystallization powder (alloy powder) is particles (silica sol) having a very small molecular weight, and is used for filtration and cleaning. Since it is removed as a filtrate at the time, it does not remain in the recovered cake-like crystallization powder (alloy powder).

The recovered cake-like crystallization powder (alloy powder) was dried at 50 ° C. in a vacuum dryer, and then heat-treated at 150 ° C. for 2 hours in vacuum. By this heat treatment, the hydrolyzed polymer of tetraethoxysilane constituting the insulating coat layer is further subjected to dehydration polycondensation to become harder and more dense silicon dioxide (SiO ₂ ), which is the insulating coat layer. The insulation is further improved. By such an insulating coating treatment, an iron-nickel alloy powder having an insulating coating layer made of high-resistance silicon dioxide (SiO ₂ ) formed on the particle surface was obtained. The obtained alloy powder was composed of spherical particles having a smooth surface. The particle size distribution was sharp, the average particle size was 0.42 μm, and the thickness of the insulating coat layer was estimated to be about 0.015 μm (about 15 nm). In addition, the powder resistivity (applied pressure: 64 MPa) significantly increased from 0.04 Ω · cm before the insulation coat treatment to over the measurement range (> ¹⁰⁷ Ω · cm) due to the insulation coating treatment.

[Example 13]
In Example 13, an iron-nickel alloy powder (iron-nickel-cobalt) containing 80 mol% of iron (Fe), 10 mol% of nickel (Ni) and 10 mol% of cobalt (Co) was according to the procedure shown in FIG. Cobalt powder) was prepared. In Example 13, when preparing the reaction solution, a metal salt raw material solution at room temperature was added to the reducing solution heated using a water bath and mixed.

<Preparation process>
The same raw materials as in Example 4 were prepared as a water-soluble iron salt, a water-soluble nickel salt, a nucleating agent, a complexing agent, a reducing agent, a pH adjuster, and an amine compound. In addition, cobalt sulfate heptahydrate (CoSO _{4.7H 2} _O , molecular weight: 281.103, reagent manufactured by Wako Pure Chemical Industries, Ltd.) was prepared as a water-soluble cobalt salt.

<Crystalization process>
(A) Preparation of metal salt raw material solution Ferrous sulfate heptahydrate (water-soluble iron salt), nickel sulfate hexahydrate (water-soluble nickel salt), cobalt sulfate heptahydrate (water-soluble cobalt salt), A metal salt raw material solution containing palladium (II) chloride ammonium (nucleating agent), trisodium citrate dihydrate (complexing agent) and water was prepared. At this time, in the obtained metal salt raw material solution, the amount of palladium (Pd) is weighed so as to be 0.38 mass ppm (0.2 mol ppm) with respect to the total amount of magnetic metals (Fe, Ni and Co). gone. Further, weighing was performed so that the amount of trisodium citrate with respect to the total amount of magnetic metals (Fe, Ni and Co) was 0.362 (36.2 mol%) in terms of molar ratio. Specifically, ferrous sulfate heptahydrate: 394.1 g, nickel sulfate hexahydrate: 46.6 g, cobalt sulfate heptahydrate: 49.8 g, palladium (II) chloride ammonium: 100.8 μg. , And trisodium citrate dihydrate: 188.7 g was dissolved in pure water: 1000 mL to prepare a metal salt raw material solution.

(B) Preparation of reducing agent solution A reducing agent solution containing sodium hydroxide (pH adjuster), hydrazine (reducing agent) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, weighing was performed so that the amount of hydrazine with respect to the total amount of magnetic metals (Fe, Ni and Co) was 3.65 in terms of molar ratio. Further, weighing was performed so that the amount of sodium hydroxide with respect to the total amount of magnetic metals (Fe, Ni and Co) was 7.07 in terms of molar ratio. Specifically, 501 g of sodium hydroxide is dissolved in 1227 mL of pure water to prepare a sodium hydroxide solution, and 60% by mass of hydrazine hydrate: 540 g is added to and mixed with this sodium hydroxide solution to prepare a reducing agent solution. Was prepared.

(D) Preparation of amine compound solution An amine compound solution containing ethylenediamine (amine compound) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, the amount of ethylenediamine blended with respect to the total amount of magnetic metals (Fe, Ni and Co) is as small as 0.01 (1.0 mol%) in terms of molar ratio. Weighing was done. Specifically, 1.07 g of ethylenediamine was dissolved in 18 mL of pure water to prepare an amine compound solution.

(E) Preparation of reaction solution and precipitation of crystallization powder The prepared metal salt raw material solution was placed in a Teflon (registered trademark) -coated stainless steel container (reaction tank) with a stirring blade installed in a water bath, and the liquid temperature was 85. The mixture was heated while stirring to reach ° C. Then, a metal salt raw material solution having a liquid temperature of 25 ° C. was added to and mixed with the reducing agent solution heated in a water bath for a mixing time of 10 seconds to obtain a reaction liquid having a liquid temperature of 70 ° C. The concentration of the magnetic metal (Fe, Ni and Co) in the reaction solution was 31.2 g / L. As a result, the reduction reaction (crystallization reaction) was started (reaction start temperature 70 ° C.). The temperature of the reaction solution continued to rise by heating with a water bath after the start of the reaction, and was maintained at the liquid temperature of 85 ° C. 10 minutes after the start of the reaction (reaction holding temperature 85 ° C.). The color tone of the reaction solution was dark green immediately after the start of the reaction (preparation of the reaction solution), but changed to dark gray after a few minutes. The color tone immediately after the start of the reaction turned dark green because the reaction proceeded according to the above formula (6), and iron hydroxide (Fe (OH) ₂ ), nickel hydroxide (Ni (OH) ₂ ), and water. It is considered that a co-precipitate of cobalt oxide (Co (OH) ₂ ) was formed in the reaction solution. The color tone changed to dark gray several minutes after the start of the reaction, probably because nucleation occurred due to the action of the nucleating agent (palladium salt).

The amine compound solution was added dropwise to the reaction solution over 10 minutes from 3 minutes to 13 minutes after the start of the reaction when the color tone of the reaction solution changed to dark gray, and the reduction reaction proceeded. As a result, iron-nickel-cobalt crystallization powder was deposited in the reaction solution. The color tone of the reaction solution at this time was black, but the supernatant solution of the reaction solution became transparent within 40 minutes from the start of the reaction. It is considered that the reduction reaction of the above formula (6) was completed and all of the iron component, nickel component and cobalt component in the reaction solution were reduced to metallic iron, metallic nickel and metallic cobalt. The reaction solution after the reaction was completed was a slurry containing iron-nickel-cobalt crystallization powder.

<Recovery process>
The slurry-like reaction liquid obtained in the crystallization step was subjected to filtration washing and solid-liquid separation treatment to recover cake-like iron-nickel-cobalt crystallization powder. Filtration washing was performed using pure water having a conductivity of 1 μS / cm until the conductivity of the filtrate filtered from the slurry became 10 μS / cm or less. The recovered cake-like crystallization powder was dried in a vacuum dryer set at 50 ° C. Then, the dried crystallization powder was cooled to 35 ° C. in a vacuum, and then nitrogen gas containing 1.0% by volume of oxygen was supplied to slowly oxidize the crystallization powder. In this way, an iron-nickel-cobalt alloy powder was obtained. The obtained alloy powder was composed of spherical particles having a smooth surface. The particle size distribution was sharp and the average particle size was 0.42 μm.

[Example 14]
In Example 14, an iron-nickel alloy powder (iron-nickel-cobalt) containing 70 mol% of iron (Fe), 10 mol% of nickel (Ni) and 20 mol% of cobalt (Co) was according to the procedure shown in FIG. (Alloy powder) was produced. In Example 14, when preparing the reaction solution, a metal salt raw material solution at room temperature was added to the reducing solution heated using a water bath and mixed.

<Preparation process>
The same raw materials as in Example 13 were prepared as a water-soluble iron salt, a water-soluble nickel salt, a water-soluble cobalt salt, a nucleating agent, a complexing agent, a reducing agent, a pH adjuster, and an amine compound.

<Crystalization process>
(A) Preparation of metal salt raw material solution Ferrous sulfate heptahydrate (water-soluble iron salt), nickel sulfate hexahydrate (water-soluble nickel salt), cobalt sulfate heptahydrate (water-soluble cobalt salt), A metal salt raw material solution containing palladium (II) chloride ammonium (nucleating agent), trisodium citrate dihydrate (complexing agent) and water was prepared. At this time, in the obtained metal salt raw material solution, the amount of palladium (Pd) is weighed so as to be 0.38 mass ppm (0.2 mol ppm) with respect to the total amount of magnetic metals (Fe, Ni and Co). gone. Further, weighing was performed so that the amount of trisodium citrate with respect to the total amount of magnetic metals (Fe, Ni and Co) was 0.362 (36.2 mol%) in terms of molar ratio. Specifically, ferrous sulfate heptahydrate: 343.0 g, nickel sulfate hexahydrate: 46.3 g, cobalt sulfate heptahydrate: 99.1 g, palladium (II) chloride ammonium: 100.2 μg. , And disodium citrate dihydrate: 187.6 g was dissolved in pure water: 1100 mL to prepare a metal salt raw material solution.

(B) Preparation of reducing agent solution A reducing agent solution containing sodium hydroxide (pH adjuster), hydrazine (reducing agent) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, weighing was performed so that the amount of hydrazine with respect to the total amount of magnetic metals (Fe, Ni and Co) was 1.46 in terms of molar ratio. Further, weighing was performed so that the amount of sodium hydroxide with respect to the total amount of magnetic metals (Fe, Ni and Co) was 7.07 in terms of molar ratio. Specifically, sodium hydroxide: 499 g is dissolved in pure water: 1221 mL to prepare a sodium hydroxide solution, and 60% by mass of hydrazine hydrate: 215 g is added to and mixed with this sodium hydroxide solution to prepare a reducing agent solution. Was prepared.

(D) Preparation of amine compound solution An amine compound solution containing ethylenediamine (amine compound) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, the amount of ethylenediamine blended with respect to the total amount of magnetic metals (Fe, Ni and Co) is as small as 0.01 (1.0 mol%) in terms of molar ratio. Weighing was done. Specifically, 1.06 g of ethylenediamine was dissolved in 18 mL of pure water to prepare an amine compound solution.

(E) Preparation of reaction solution and precipitation of crystallization powder The prepared metal salt raw material solution was placed in a Teflon (registered trademark) -coated stainless steel container (reaction tank) with a stirring blade installed in a water bath, and the liquid temperature was 85. The mixture was heated while stirring to reach ° C. Then, a metal salt raw material solution having a liquid temperature of 25 ° C. was added to and mixed with the reducing agent solution heated in a water bath for a mixing time of 10 seconds to obtain a reaction liquid having a liquid temperature of 67 ° C. The concentration of the magnetic metal (Fe, Ni and Co) in the reaction solution was 33.7 g / L. As a result, the reduction reaction (crystallization reaction) was started (reaction start temperature 67 ° C.). The temperature of the reaction solution continued to rise by heating with a water bath after the start of the reaction, and was maintained at the liquid temperature of 85 ° C. 10 minutes after the start of the reaction (reaction holding temperature 85 ° C.). The color tone of the reaction solution was dark green immediately after the start of the reaction (preparation of the reaction solution), but changed to dark gray after a few minutes. The color tone immediately after the start of the reaction turned dark green because the reaction proceeded according to the above formula (6), and iron hydroxide (Fe (OH) ₂ ), nickel hydroxide (Ni (OH) ₂ ), and water. It is considered that a co-precipitate of cobalt oxide (Co (OH) ₂ ) was formed in the reaction solution. The color tone changed to dark gray several minutes after the start of the reaction, probably because nucleation occurred due to the action of the nucleating agent (palladium salt).

<Recovery process>
The slurry-like reaction liquid obtained in the crystallization step was subjected to filtration washing and solid-liquid separation treatment to recover cake-like iron-nickel-cobalt crystallization powder. Filtration washing was performed using pure water having a conductivity of 1 μS / cm until the conductivity of the filtrate filtered from the slurry became 10 μS / cm or less. The recovered cake-like crystallization powder was dried in a vacuum dryer set at 50 ° C. Then, the dried crystallization powder was cooled to 35 ° C. in a vacuum, and then nitrogen gas containing 1.0% by volume of oxygen was supplied to slowly oxidize the crystallization powder. In this way, an iron-nickel-cobalt alloy powder was obtained. The obtained alloy powder was composed of spherical particles having a smooth surface. The particle size distribution was sharp and the average particle size was 0.40 μm.

[Example 15]
In Example 15, an iron-nickel alloy powder (iron-nickel-cobalt) containing 65 mol% of iron (Fe), 10 mol% of nickel (Ni) and 25 mol% of cobalt (Co) was according to the procedure shown in FIG. (Alloy powder) was produced. In Example 15, when preparing the reaction solution, a metal salt raw material solution at room temperature was added to the reducing solution heated using a water bath and mixed.

<Crystalization process>
(A) Preparation of metal salt raw material solution Ferrous sulfate heptahydrate (water-soluble iron salt), nickel sulfate hexahydrate (water-soluble nickel salt), cobalt sulfate heptahydrate (water-soluble cobalt salt), A metal salt raw material solution containing palladium (II) chloride ammonium (nucleating agent), trisodium citrate dihydrate (complexing agent) and water was prepared. At this time, in the obtained metal salt raw material solution, the amount of palladium (Pd) is weighed so as to be 0.37 mass ppm (0.2 mol ppm) with respect to the total amount of magnetic metals (Fe, Ni and Co). gone. Further, weighing was performed so that the amount of trisodium citrate with respect to the total amount of magnetic metals (Fe, Ni and Co) was 0.362 (36.2 mol%) in terms of molar ratio. Specifically, ferrous sulfate heptahydrate: 317.6 g, nickel sulfate hexahydrate: 46.2 g, cobalt sulfate heptahydrate: 123.5 g, palladium (II) chloride ammonium: 100.0 μg. , And disodium citrate dihydrate: 187.1 g was dissolved in pure water: 1100 mL to prepare a metal salt raw material solution.

(B) Preparation of reducing agent solution A reducing agent solution containing sodium hydroxide (pH adjuster), hydrazine (reducing agent) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, weighing was performed so that the amount of hydrazine with respect to the total amount of magnetic metals (Fe, Ni and Co) was 1.47 in terms of molar ratio. Further, weighing was performed so that the amount of sodium hydroxide with respect to the total amount of magnetic metals (Fe, Ni and Co) was 7.07 in terms of molar ratio. Specifically, sodium hydroxide: 497 g is dissolved in pure water: 1216 mL to prepare a sodium hydroxide solution, and 60% by mass of hydrazine hydrate: 215 g is added to and mixed with this sodium hydroxide solution to prepare a reducing agent solution. Was prepared.

The amine compound solution was added dropwise to the reaction solution over 10 minutes from 3 minutes to 13 minutes after the start of the reaction when the color tone of the reaction solution changed to dark gray, and the reduction reaction proceeded. As a result, iron-nickel-cobalt crystallization powder was deposited in the reaction solution. The color tone of the reaction solution at this time was black, but the supernatant solution of the reaction solution became transparent within 30 minutes from the start of the reaction. It is considered that the reduction reaction of the above formula (6) was completed and all of the iron component, nickel component and cobalt component in the reaction solution were reduced to metallic iron, metallic nickel and metallic cobalt. The reaction solution after the reaction was completed was a slurry containing iron-nickel-cobalt crystallization powder.

[Comparative Example 1]
In Comparative Example 1, palladium (II) chloride ammonium (nucleating agent) was not added when preparing the metal salt raw material solution. Other than that, the reaction solution was prepared and the crystallization powder was precipitated in the same manner as in Example 1, and iron-nickel alloy powder (iron-) containing 50 mol% of iron (Fe) and 50 mol% of nickel (Ni). Nickel alloy powder) was prepared. The concentration of magnetic metals (Fe and Ni) in the reaction solution was 32.3 g / L. The obtained alloy powder was composed of spherical particles, and the surface of these particles was uneven. The particle size distribution was sharp and the average particle size was 0.65 μm.

[Comparative Example 2]
In Comparative Example 2, trisodium citrate dihydrate (complexing agent) was not added when preparing the metal salt raw material solution. Other than that, the reaction solution was prepared and the crystallization powder was precipitated in the same manner as in Example 1, and iron-nickel alloy powder (iron-) containing 50 mol% of iron (Fe) and 50 mol% of nickel (Ni). Nickel alloy powder) was prepared. The concentration of magnetic metals (Fe and Ni) in the reaction solution was 33.3 g / L. The obtained alloy powder was composed of particles having a distorted shape, and the surface of these particles was uneven. The particle size distribution was broad and the average particle size was 0.26 μm.

[Comparative Example 3]
In Comparative Example 3, palladium (II) chloride ammonium (nuclear agent) and trisodium citrate dihydrate (complexing agent) were not blended when preparing the metal salt raw material solution. Further, when preparing the reducing agent solution, a large amount of hydrazine (reducing agent) was added. An iron-nickel alloy powder (iron-nickel alloy powder) was produced in the same manner as in Example 1 except for the above. The metal salt raw material solution and the reducing agent solution were prepared as shown below.

(A) Preparation of metal salt raw material solution A metal salt raw material solution containing ferrous chloride tetrahydrate (water-soluble iron salt), nickel chloride hexahydrate (water-soluble nickel salt), and water was prepared. Specifically, 173.60 g of ferrous chloride tetrahydrate and 207.55 g of nickel chloride hexahydrate were dissolved in 1200 mL of pure water to prepare a metal salt raw material solution.

(B) Preparation of reducing agent solution A reducing agent solution containing sodium hydroxide (pH adjuster), hydrazine (reducing agent) and water was prepared. At this time, in the reaction solution prepared in the subsequent crystallization step, weighing was performed so that the amount of hydrazine with respect to the total amount of magnetic metals (Fe and Ni) was 19.4 in terms of molar ratio. Further, weighing was performed so that the amount of sodium hydroxide with respect to the amount of magnetic metals (Fe and Ni) was 4.96 in terms of molar ratio. Specifically, sodium hydroxide: 346 g is dissolved in pure water: 850 mL to prepare a sodium hydroxide solution, and 60% by mass of hydrazine hydrate: 2828 g is added to and mixed with this sodium hydroxide solution to prepare a reducing agent solution. Was prepared. The reducing agent solution was used after being heated to a liquid temperature of 37 ° C. so that the reaction starting temperature would be 55 ° C. when the reducing agent solution was added and mixed with the metal salt raw material solution.

The obtained alloy powder was composed of spherical particles having a relatively smooth surface. The particle size distribution was broad and the average particle size was 0.22 μm.

Table 1 summarizes the production conditions of the alloy powders of Examples 1 to 15 and Comparative Examples 1 to 3 above.

(2) Evaluation of Iron-Nickel Alloy Powder Various characteristics of the iron-nickel alloy powder obtained in Examples 1 to 15 and Comparative Examples 1 to 3 were evaluated as follows.

<Composition analysis>
X-ray diffraction (XRD) measurement was performed using an X-ray diffractometer, and the presence or absence of alloy powder formation was confirmed from the obtained XRD data.

<Analysis of metal impurities>
The content of impurities was analyzed. The amount of oxygen is measured by an inert gas melting method using an oxygen analyzer (manufactured by LECO Corporation, TC436), and the amount of carbon and the amount of sulfur are measured by a combustion method using a carbon sulfur analyzer (manufactured by LECO Corporation, CS600). Measured at. The amount of chlorine was measured using a fluorescent X-ray analyzer (Magix, manufactured by Spectris Co., Ltd.), and the amount of silicon and the amount of sodium were measured using an ICP emission spectrophotometer (5100, manufactured by Agilent Technologies, Inc.).

<Particle size (average particle size, coefficient of variation)>
The alloy powder was observed with a scanning electron microscope (SEM; manufactured by JEOL Ltd., JSM-7100F) (magnification: 5000 to 80,000 times). The observed image (SEM image) was image-analyzed, and from the result, the standard deviation of the average particle size and the particle size obtained by the number average was calculated. Further, the coefficient of variation (CV value) was calculated according to the following equation (14) to obtain the particle size (average particle size, coefficient of variation) of the alloy powder.

<Intraparticle composition analysis>
The alloy powder embedded in the resin is thinned to a thickness of about 100 nm using a focused ion beam (FIB) device, and the cross section of the alloy particles is scanned in the processed sample with a scanning transmission electron microscope (STEM; Observed with HD-2300A) manufactured by Hitachi High Technologies. The observation was carried out under the condition of magnification: 100,000 to 200,000 times. Then, the composition distribution in the alloy particles was determined by line analysis using an energy dispersive X-ray spectroscopy (EDS) apparatus. At this time, the composition was calculated from the number of detection counts of the characteristic X-rays (K-rays) of the measurement element.

<Crystal diameter>
The alloy powder was analyzed by the X-ray diffraction (XRD) method, and the crystallite diameter was evaluated from the half-value width of the X-ray diffraction peak on the (111) plane based on the Scherrer equation. The XRD measurement conditions were the same as for the composition analysis. The crystallinity indicates the degree of crystallization, and the larger the crystallinity, the higher the crystallinity.

<Cross powder density>
The green compact density of the alloy powder was evaluated. Specifically, about 0.3 g of alloy powder was filled in the columnar hole portion (inner diameter 5 mm) of the mold. Then, using a press machine, the pellet was formed into a pellet shape having a diameter of 5 mm and a height of 3 to 4 mm at a pressure of 100 MPa. The mass and height of the obtained pellets were measured at room temperature to calculate the powder compact density.

<Cross powder resistivity>
The green compact resistivity of the alloy powder was measured using a powder resistance measuring system (MCP-PD51 manufactured by Mitsubishi Chemical Analytech), and the conductivity (insulation) was evaluated. Specifically, about 4 g of alloy powder is filled in the columnar sample chamber of the device, and a pressure of 64 MPa is applied using the press machine attached to the device, and the powder resistivity (unit: Ω ·. cm) was calculated.

<Magnetic characteristics (saturation magnetic flux density, coercive force)>
Measurements were performed using a vibration sample magnetometer (VSM), and the magnetic characteristics (saturated magnetic flux density (T: Tesla), coercive force (A / m)) of the alloy powder were evaluated. The values of saturation magnetic flux density and coercive force were calculated from the BH curve (magnetic hysteresis curve) obtained by the measurement. Since the alloy powder obtained in Comparative Example 2 has a distorted shape and cannot be applied to an element such as an inductor, the magnetic characteristics were not measured.

(3) Evaluation Results Table 2 summarizes the evaluation results obtained for Examples 1 to 15 and Comparative Examples 1 to 3. Further, SEM images of the alloy powders obtained in Examples 1, 2, 10, 13 and 14 are shown in FIGS. 8, 9, 13, 15, and 16, respectively, and the alloy powders obtained in Example 6 are shown. The SEM images of are shown in FIGS. 10 (a) and 10 (b). Here, FIG. 10A is an SEM image of the alloy powder before the spiral jet crushing treatment, and FIG. 10B is an SEM image of the alloy powder after the spiral jet crushing treatment. Further, STEM images and EDS line analysis results of the particle cross sections of the alloy powders obtained in Examples 8 and 9 are shown in FIGS. 11 (a), 11 (b) and 12, respectively. Here, FIG. 11 (a) shows the STEM image and EDS line analysis result of the particle cross section of the alloy powder before the high temperature heat treatment, and FIG. 11 (b) shows the STEM image and EDS line analysis of the particle cross section of the alloy powder after the high temperature heat treatment. The result. The SEM images of the alloy powder obtained in Example 12 are shown in FIGS. 14 (a) and 14 (b). Here, FIG. 14A is an SEM image of the alloy powder before the insulation coating treatment, and FIG. 14B is an SEM image of the alloy powder after the insulation coating treatment. Further, SEM images of the respective alloy powders obtained in Comparative Examples 1 to 3 are shown in FIGS. 17 to 19.

Examples 1, 3 and Comparative Examples 1 to 3 are examples in which iron-nickel alloy powder was produced with the reaction start temperature in the crystallization step set to 55 ° C and the reaction holding temperature set to 70 ° C. In Examples 1 and 3 using a very small amount of a specific nucleating agent and complexing agent, the obtained alloy powder had an average particle size of 0, even though the amount of hydrazine used as a reducing agent was small. It was as fine as 40 to 0.41 μm, had a small CV value, and had a sharp particle size distribution. Further, this alloy powder was spherical and had a smooth surface.

On the other hand, in Comparative Example 1 in which no nucleating agent was used, the obtained alloy powder had a large average particle size of 0.65 μm as compared with Example 1 and Example 3, and it was difficult to make the alloy powder finer. Although it was spherical, the surface unevenness was large. In Comparative Example 2 in which no complexing agent was used, the average particle size of the obtained alloy powder was as fine as 0.26 μm, but the CV value was large and the particle size distribution was wide. Moreover, the alloy powder had a large surface unevenness and a distorted shape. In Comparative Example 3 in which a large amount of reducing agent (hydrazine) was blended without using a nucleating agent and a complexing agent, the obtained alloy powder was a spherical powder having a relatively smooth surface. It is considered that this is because the reduction reaction worked strongly by blending a large amount of hydrazine. The obtained alloy powder had an average particle size of 0.22 μm, which was fine. However, the CV value was large and the particle size distribution was wide.

Example 2 is an example of producing an iron-nickel-cobalt alloy powder using a specific nucleating agent and a complexing agent with a reaction starting temperature of 55 ° C. and a reaction holding temperature of 70 ° C. in the crystallization step. Despite the small amount of hydrazine used as the reducing agent, the obtained alloy powder had a fine average particle size of about 0.3 μm and a sharp particle size distribution. The surface of this alloy powder was smooth and spherical. The saturation magnetization of the alloy powder was high.

In Example 5, an additional raw material solution containing a water-soluble nickel salt was added and mixed with the reaction solution during crystallization, and 51 mol% of iron (Fe) and 49 mol% of nickel (Ni) having a nickel-rich surface composition were added and mixed. This is an example of producing an iron-nickel alloy powder containing. A dense oxide film is formed due to the nickel-rich surface composition, and the amount of oxidation on the particle surface is suppressed. Therefore, this alloy powder is not only more stable in the atmosphere, but also has excellent magnetic properties such as saturation magnetic flux density.

Example 6 is an example in which a crystallization powder as a dry powder obtained through a crystallization step and a recovery step is subjected to a spiral jet crushing treatment to produce a spherical iron-nickel alloy powder having a very smooth surface. .. Further, Example 7 is an example in which a slurry-like crystallization powder in the middle of the recovery process after the crystallization process is subjected to a high-pressure fluid collision crushing treatment to produce a spherical and extremely smooth iron-nickel alloy powder. be. In addition to the smooth surface, these alloy powders also have reduced agglomerated particles. Therefore, the filling property is improved (the powder compact density is increased). Further, by reducing the number of agglomerated particles, improvement of eddy current loss through the particles can be expected.

In Example 8, the iron (Fe) 65 obtained by subjecting the crystallization powder obtained in the crystallization step to a reaction start temperature of 71 ° C. and a reaction holding temperature of 80 ° C. to a high temperature heat treatment to improve the composition uniformity in the particles. This is an example of producing an iron-nickel alloy powder containing mol% and nickel (Ni) 35 mol%. As is clear from FIG. 11B, this alloy powder has a uniform composition (65 mol% of iron and 35 mol% of nickel) in the particles, and is a low thermal expansion material other than the soft magnetic material. It can also be expected to be used as (Invar alloy).

In Example 9, an additional raw material solution containing a water-soluble nickel salt was added and mixed with the reaction solution during crystallization, and 65 mol% of iron (Fe) and 35 mol% of nickel (Ni) having a nickel-rich surface composition were added and mixed. This is an example of producing an iron-nickel alloy powder containing. As is clear from FIG. 12, a nickel-rich layer having a thickness of about 10 to 15 nm is formed on the particle surface, and a dense oxide film due to this nickel-rich surface composition is formed to suppress the amount of oxidation on the particle surface. Will be done. Therefore, this alloy powder is not only more stable in the atmosphere, but also has excellent magnetic properties such as saturation magnetic flux density.

In Examples 10 and 11, an additional raw material solution containing a water-soluble nickel salt is added and mixed with the reaction solution during crystallization to promote the reduction of iron ions (or iron hydroxide) that are difficult to reduce. Iron-nickel alloy powder containing 80 mol% iron (Fe) and 20 mol% nickel (Ni) and 90 mol% iron (Fe), which have a large iron content so that the particle surface has a more nickel-rich composition. This is an example of producing an iron-nickel alloy powder containing 10 mol% of nickel (Ni). Although the iron content is as large as 80 mol% to 90 mol% and the composition is close to that of pure iron, even if the amount of hydrazine used as a reducing agent is relatively small, reduction failure does not occur and the average particle size is 0.4 to. A spherical alloy powder having a smooth surface and a fine particle size distribution of about 0.5 μm was obtained. The saturation magnetization of the alloy powder was as high as that of pure iron powder (1.95T to 2.0T).

In Examples 8 to 11, the powder density of the obtained iron-nickel alloy powder is smaller than that in Examples 1 to 7. However, the iron-nickel alloy powder of Examples 1 to 7 (iron-nickel alloy powder containing 56 to 50 mol% Fe and 44 to 50 mol% Ni, iron-nickel containing 50 mol% Fe, 40 mol% Ni and 10 mol% Co). -Cobalt alloy powder) has a true specific gravity of 8.2 to 8.25, whereas the iron-nickel alloy powders of Examples 8 and 9 (iron-nickel alloy powder containing 65 mol% Fe and 35 mol% Ni) The true specific gravity is 8.1, the true specific gravity of the iron-nickel alloy powder of Example 10 (iron-nickel alloy powder containing 80 mol% Fe and 20 mol% Ni) is 8.0, and the iron-nickel alloy of Example 11 The true specific gravity of the powder (iron-nickel alloy powder containing 90 mol% Fe and 10 mol% Ni) is 7.9, and the true specific gravity of the iron-nickel alloy powder decreases as the iron content increases. For example, it can be seen that the green compact density according to each example is good.

In Example 12, iron-nickel obtained by subjecting the crystallization powder as a dry powder obtained through the crystallization step and the recovery step to an insulating coating treatment and coating the particle surface with high-resistance silicon dioxide (SiO ₂ ). This is an example of producing a system alloy powder. Since this alloy powder has significantly improved insulating properties between particles (resistivity of green compacts has greatly increased), improvement of eddy current loss between particles can be expected.

In Examples 13 to 15, a water-soluble cobalt salt is contained in addition to a water-soluble iron salt and a water-soluble nickel salt in a magnetic metal source to promote the reduction of iron ions (or iron hydroxide) that are difficult to reduce, and cobalt. This is an example of producing an iron-nickel alloy powder having a high content ratio of 10 mol% to 25 mol% and a large iron content ratio of 65 mol% to 80 mol%. Specifically, iron-nickel-cobalt alloy powder containing 80 mol% Fe, 10 mol% Ni and 10 mol% Co, iron-nickel-cobalt alloy powder containing 70 mol% Fe, 10 mol% Ni and 20 mol% Co, and 65 mol Fe. This is an example of producing an iron-nickel-cobalt alloy powder containing%, Ni 10 mol% and Co 25 mol%. Although the iron content is as large as 65 mol% to 80 mol%, the spherical alloy powder does not cause reduction failure even when the amount of hydrazine used as a reducing agent is very small due to the effect of promoting the reduction reaction by adding cobalt. Obtained. The alloy powder had a fine average particle size of about 0.4 μm, a sharp particle size distribution, and a smooth surface. The saturation magnetization of the alloy powder was as high as or higher than that of pure iron powder (1.95T to 2.0T).

Further, the true specific gravity of the iron-nickel alloy powder (iron-nickel-cobalt alloy powder) obtained in Examples 13 to 15 is estimated to be about 8.0 to 8.1, but the powder density in each case is estimated to be about 8.0 to 8.1. Was large and good. It is considered that this is because the reduction reaction was completed before the aggregation of the particles proceeded due to the reduction reaction promoting effect of the addition of cobalt, and as a result, the aggregation of the particles during crystallization was suppressed. It is also considered that the promotion of spheroidization, which is another action of the addition of cobalt, improves the filling property of the particles.

Claims

A method for producing an iron (Fe) -nickel (Ni) alloy powder containing at least iron (Fe) and nickel (Ni) as magnetic metals, wherein the method is as follows;
Preparation process for preparing magnetic metal sources, nucleating agents, complexing agents, reducing agents, and pH adjusters as starting materials,
A crystallization step of preparing a reaction solution containing the starting material and water and crystallizing the crystallization powder containing the magnetic metal in the reaction solution by a reduction reaction, and recovering the crystallization powder from the reaction solution. With a collection process,
The magnetic metal source contains a water-soluble iron salt and a water-soluble nickel salt, and contains.
The nucleating agent is a water-soluble salt of a metal that is noble than nickel.
The complexing agent is at least one selected from the group consisting of hydroxycarboxylic acids, salts of hydroxycarboxylic acids, and derivatives of hydroxycarboxylic acids.
The reducing agent is hydrazine (N 2 H 4 ).
The method, wherein the pH regulator is alkali hydroxide.
The water-soluble iron salt is at least one selected from the group consisting of ferrous chloride (FeCl 2 ), ferrous sulfate (FeSO 4 ), and ferrous nitrate (Fe (NO 3 ) 2 ). Item 1. The method according to Item 1.
The water-soluble nickel salt is at least one selected from the group consisting of nickel chloride (NiCl 2 ), nickel sulfate (NiSO 4 ), and nickel nitrate (Ni (NO 3 ) 2 ), according to claim 1 or 2. the method of.
The method according to any one of claims 1 to 3, wherein the nucleating agent is at least one selected from the group consisting of a copper salt, a palladium salt, and a platinum salt.
The complexing agent is at least one hydroxycarboxylic acid selected from tartaric acid ((CH (OH) COOH) 2 ) and citric acid (C (OH) (CH 2 COOH) 2 COOH), claims 1 to 4. The method described in any one of the above.
The method according to any one of claims 1 to 5, wherein the pH adjuster is at least one selected from sodium hydroxide (NaOH) and potassium hydroxide (KOH).
The magnetic metal further contains cobalt (Co) and
The method according to any one of claims 1 to 6, wherein the magnetic metal source further contains a water-soluble cobalt salt.
In the magnetic metal, the iron (Fe) content is 60 mol% or more and 85 mol% or less, and the cobalt (Co) content is 10 mol% or more and 30 mol% or less.
The seventh aspect of the present invention, wherein the content ratio of the water-soluble iron salt is 60 mol% or more and 85 mol% or less, and the content ratio of the water-soluble cobalt salt is 10 mol% or more and 30 mol% or less in the magnetic metal source. the method of.
The water-soluble cobalt salt is at least one selected from the group consisting of cobalt chloride (CoCl 2 ), cobalt sulfate (CoSO 4 ), and cobalt nitrate (Co (NO 3 ) 2 ), according to claim 7 or 8. the method of.
The starting material is two or more primary amino groups (-NH 2 ), one primary amino group (-NH 2 ) and one or more secondary amino groups (-NH-), or The method according to any one of claims 1 to 9, further comprising an amine compound containing two or more secondary amino groups (-NH-) in the molecule.
The method according to claim 10, wherein the amine compound is at least one of an alkylene amine and an alkylene amine derivative.
The eleventh claim, wherein the alkyleneamine and / or the alkyleneamine derivative has at least the structure represented by the following (A), in which the nitrogen atom of the amino group in the molecule is bonded via a carbon chain having two carbon atoms. the method of.
The amine compounds include ethylenediamine (H 2 NC 2 H 4 NH 2 ), diethylene triamine (H 2 NC 2 H 4 NHC 2 H 4 NH 2 ), and triethylene tetramine (H 2 N (C 2 H 4 NH) 2 C 2 ). H 4 NH 2 ), tetraethylene pentamine (H 2 N (C 2 H 4 NH) 3 C 2 H 4 NH 2 ), pentaethylene hexamine (H 2 N (C 2 H 4 NH) 4 C 2 H 4 NH) 2 ), and at least one alkylene amine selected from the group consisting of propylene diamine (CH 3 CH (NH 2 ) CH 2 NH 2 ) and / or tris (2-aminoethyl) amine (N (C 2 H 4 NH). 2 ) 3 ), N- (2-aminoethyl) ethanolamine (H 2 NC 2 H 4 NHC 2 H 4 OH), N- (2-aminoethyl) propanolamine (H 2 NC 2 H 4 NHC 3 H 6 ) OH), 2,3-diaminopropionic acid (H 2 NCH 2 CH (NH) COOH), ethylenediamine-N, N'-diacetic acid (HOOCCH 2 NHC 2 H 4 NHCH 2 COOH), and 1,2-cyclohexanediamine. The method according to any one of claims 10 to 12, which is at least one alkylene amine derivative selected from the group consisting of (H 2 NC 6 H10NH 2 ).
The method according to any one of claims 10 to 13, wherein the blending amount of the amine compound with respect to the total amount of the magnetic metals is 0.01 mol% or more and 5.00 mol% or less.
When preparing the reaction solution in the crystallization step, a metal salt raw material solution in which the magnetic metal source, the nucleating agent, and the complexing agent are dissolved in water, and a reducing agent solution in which the reducing agent is dissolved in water are used. And a pH-adjusting solution in which the pH-adjusting agent is dissolved in water are prepared, and the metal salt raw material solution and the pH-adjusting solution are mixed to form a mixed solution, and the mixed solution and the reducing agent solution are mixed. The method according to any one of claims 1 to 14.
The method according to claim 15, wherein when preparing the reaction solution, the pH adjusting solution and the reducing agent solution are sequentially added to the metal salt raw material solution and mixed.
The method according to claim 15 or 16, wherein the time required for mixing the mixed solution and the reducing agent solution is 1 second or more and 180 seconds or less.
When preparing the reaction solution in the crystallization step, the metal salt raw material solution in which the magnetic metal source, the nucleating agent, and the complexing agent are dissolved in water, and the reducing agent and the pH adjusting agent are dissolved in water. The method according to any one of claims 1 to 14, wherein each of the prepared reducing agent solutions is prepared, and the metal salt raw material solution and the reducing agent solution are mixed.
The method according to claim 18, wherein when preparing the reaction solution, the reducing agent solution is added to the metal salt raw material solution, or conversely, the metal salt raw material solution is added to the reducing agent solution and mixed. ..
The method according to claim 18 or 19, wherein the time required for mixing the metal salt raw material solution and the reducing agent solution is 1 second or more and 180 seconds or less.
In the crystallization step, before the reduction reaction is completed, an additional raw material solution prepared by dissolving at least one of the water-soluble nickel salt and the water-soluble cobalt salt in water is further added to the reaction solution and mixed. The method according to any one of claims 1 to 20.
The method according to any one of claims 15 to 21, wherein the amine compound is blended in at least one of the metal salt raw material solution, the reducing agent solution, the pH adjusting solution, and the reaction solution.
The temperature of the reaction solution at the start of crystallization of the crystallization powder (reaction start temperature) is 40 ° C. or higher and 90 ° C. or lower, and the temperature of the reaction solution held during crystallization after the start of crystallization (reaction holding temperature). The method according to any one of claims 1 to 22, wherein the temperature is 60 ° C. or higher and 99 ° C. or higher.
Claimed to further include a crushing step of subjecting the crystallization powder after the recovery step or the crystallization powder in the middle of the recovery step to a crushing process using collision energy to crush the aggregated particles contained in the crystallization powder. Item 2. The method according to any one of Items 1 to 23.
The method according to claim 24, wherein the crystallization powder after the recovery step is crushed by dry crushing or wet crushing, or the crystallization powder during the recovery step is crushed by wet crushing.
The method according to claim 25, wherein the drywall crushing is spiral jet crushing.
The method according to claim 25, wherein the wet crushing is high pressure fluid collision crushing.
The crystallization powder after the recovery step or the crystallization powder during the recovery step is heat-treated in an inert atmosphere, a reducing atmosphere, or a vacuum atmosphere at a temperature of more than 150 ° C. and 400 ° C. or lower, whereby iron (Fe) is applied. )-The method according to any one of claims 1 to 27, further comprising a high temperature heat treatment step for improving the composition uniformity in the particles of the nickel (Ni) alloy powder.
Insulation coating treatment is applied to the crystallization powder obtained through the recovery step to form an insulation coating layer made of a metal oxide on the particle surface of the crystallization powder, thereby improving the insulation between the particles. The method according to any one of claims 1 to 28, which is further provided.
During the insulating coating step, the crystallization powder is dispersed in a mixed solvent containing water and an organic solvent, and a metal alkoxide is further added and mixed with the mixed solvent to prepare a slurry, and the metal alkoxide is hydrolyzed in the slurry. 2. Method.
The method according to claim 30, wherein the metal alkoxide contains silicon alkoxide (alkyl silicate) as a main component, and the metal oxide contains silicon dioxide (SiO 2 ) as a main component.
The method according to claim 30 or 31, wherein the hydrolysis of the metal alkoxide is carried out in the coexistence of a base catalyst (alkali catalyst).